From b06cca35005717557b42540417c2fd7cf1282bb6 Mon Sep 17 00:00:00 2001
From: "D. Seifert" <Domiii@users.noreply.github.com>
Date: Wed, 16 Apr 2025 00:11:24 +0800
Subject: [PATCH 01/20] Replay the error message building i
 `MessageFormatter::Format`

---
 include/v8.h              |  1 +
 src/api/api.cc            |  8 ++++++++
 src/execution/messages.cc | 10 +++++++++-
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/include/v8.h b/include/v8.h
index 990466212b3c..b2575a731140 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -121,6 +121,7 @@ static bool AreAssertsDisabled();
 
 static uintptr_t RecordReplayValue(const char* why, uintptr_t v);
 static void RecordReplayBytes(const char* why, void* buf, size_t size);
+static void RecordReplayString(const char* why, std::string& str);
 
 static size_t CreateOrderedLock(const char* name);
 static void OrderedLock(int lock);
diff --git a/src/api/api.cc b/src/api/api.cc
index 33a5574d7dc1..da477c87bb6c 100644
--- a/src/api/api.cc
+++ b/src/api/api.cc
@@ -11550,6 +11550,14 @@ extern "C" DLLEXPORT void V8RecordReplayBytes(const char* why, void* buf, size_t
   recordreplay::RecordReplayBytes(why, buf, size);
 }
 
+void recordreplay::RecordReplayString(const char* why, std::string& str) {
+  size_t length = RecordReplayValue(why, str.length());
+  str.resize(length);
+  if (length) {
+    RecordReplayBytes(why, &str[0], length);
+  }
+}
+
 bool recordreplay::AreEventsDisallowed(const char* why) {
   if (IsRecordingOrReplaying("disallow-events", why)) {
     return gRecordReplayAreEventsDisallowed();
diff --git a/src/execution/messages.cc b/src/execution/messages.cc
index 25a6cba3bf55..d0387927ae4b 100644
--- a/src/execution/messages.cc
+++ b/src/execution/messages.cc
@@ -518,7 +518,15 @@ MaybeHandle<String> MessageFormatter::Format(Isolate* isolate,
     }
   }
 
-  return builder.Finish();
+
+  MaybeHandle<String> rv = builder.Finish();
+  if (recordreplay::IsRecordingOrReplEaying("MessageFormatter::Format")) {
+    // [PRO-1150] Replay error messages.
+    std::string str = rv.ToHandleChecked()->ToCString();
+    recordreplay::RecordReplayString("MessageFormatter::Format", str);
+    rv = isolate->factory()->NewStringFromUtf8(base::CStrVector(str.c_str()));
+  }
+  return rv;
 }
 
 MaybeHandle<JSObject> ErrorUtils::Construct(Isolate* isolate,

From 4a42d95883bbbe97f614f884e636322c60ae03bc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Tue, 15 Apr 2025 18:22:14 +0200
Subject: [PATCH 02/20] Remove error suppression in unregistered scripts

---
 src/api/api.cc | 24 ------------------------
 1 file changed, 24 deletions(-)

diff --git a/src/api/api.cc b/src/api/api.cc
index 33a5574d7dc1..24da84c68515 100644
--- a/src/api/api.cc
+++ b/src/api/api.cc
@@ -10969,30 +10969,6 @@ void RecordReplayOnExceptionUnwind(Isolate* isolate) {
   if (!isolate->is_catchable_by_javascript(*exception))
     return;
 
-  {
-    // Note: Most of this is copied from |ComputeLocation| in messages.cc.
-    JavaScriptFrameIterator it(isolate);
-    if (!it.done()) {
-      // Compute the location from the function and the relocation info of the
-      // baseline code. For optimized code this will use the deoptimization
-      // information to get canonical location information.
-      std::vector<FrameSummary> frames;
-      it.frame()->Summarize(&frames);
-      if (!frames.empty()) { // There might not always be a frame due to RUN-1920.
-        auto& summary = frames.back().AsJavaScript();
-        Handle<SharedFunctionInfo> shared(summary.function()->shared(), isolate);
-        Handle<Object> script(shared->script(), isolate);
-        if (script->IsScript()) {
-          Handle<Script> casted_script = Handle<Script>::cast(script);
-          if (!RecordReplayHasRegisteredScript(*casted_script)) {
-            // Don't repor errors from unregistered.
-            return;
-          }
-        }
-      }
-    }
-  }
-
   isolate->clear_pending_exception();
   Handle<Object> message(isolate->pending_message(), isolate);
   isolate->clear_pending_message();

From 8efc4c3cb322f0c463d7f69586c930f850ade397 Mon Sep 17 00:00:00 2001
From: "D. Seifert" <Domiii@users.noreply.github.com>
Date: Wed, 16 Apr 2025 00:37:21 +0800
Subject: [PATCH 03/20] whoops

---
 src/execution/messages.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/execution/messages.cc b/src/execution/messages.cc
index d0387927ae4b..8bd6fe99a3df 100644
--- a/src/execution/messages.cc
+++ b/src/execution/messages.cc
@@ -520,9 +520,9 @@ MaybeHandle<String> MessageFormatter::Format(Isolate* isolate,
 
 
   MaybeHandle<String> rv = builder.Finish();
-  if (recordreplay::IsRecordingOrReplEaying("MessageFormatter::Format")) {
+  if (recordreplay::IsRecordingOrReplaying("MessageFormatter::Format")) {
     // [PRO-1150] Replay error messages.
-    std::string str = rv.ToHandleChecked()->ToCString();
+    std::string str = rv.ToHandleChecked()->ToCString().get();
     recordreplay::RecordReplayString("MessageFormatter::Format", str);
     rv = isolate->factory()->NewStringFromUtf8(base::CStrVector(str.c_str()));
   }

From 6e722accfc78218917523bf9a0dc7ff8a139d9ba Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Wed, 16 Apr 2025 13:32:01 +0200
Subject: [PATCH 04/20] add asserts

---
 src/codegen/compiler.cc  | 2 ++
 src/objects/script-inl.h | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/src/codegen/compiler.cc b/src/codegen/compiler.cc
index dd7473e73c88..4257e1da032c 100644
--- a/src/codegen/compiler.cc
+++ b/src/codegen/compiler.cc
@@ -414,6 +414,8 @@ ScriptOriginOptions OriginOptionsForEval(
       is_opaque = true;
     }
   }
+  recordreplay::Assert("ScriptOriginOptions OriginOptionsForEval %d",
+                       is_shared_cross_origin);
   return ScriptOriginOptions(is_shared_cross_origin, is_opaque);
 }
 
diff --git a/src/objects/script-inl.h b/src/objects/script-inl.h
index 4d1af1104a70..695838da5859 100644
--- a/src/objects/script-inl.h
+++ b/src/objects/script-inl.h
@@ -155,6 +155,8 @@ void Script::set_is_repl_mode(bool value) {
 }
 
 ScriptOriginOptions Script::origin_options() {
+  recordreplay::Assert("ScriptOriginOptions Script::origin_options %d",
+                       OriginOptionsBits::decode(flags()));
   return ScriptOriginOptions(OriginOptionsBits::decode(flags()));
 }
 void Script::set_origin_options(ScriptOriginOptions origin_options) {

From 6498e9b82a26ace67cade5178f61bfe9a222ca4a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Wed, 16 Apr 2025 14:07:52 +0200
Subject: [PATCH 05/20] try prints

---
 src/codegen/compiler.cc  | 2 +-
 src/objects/script-inl.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/codegen/compiler.cc b/src/codegen/compiler.cc
index 4257e1da032c..b5b52345658b 100644
--- a/src/codegen/compiler.cc
+++ b/src/codegen/compiler.cc
@@ -414,7 +414,7 @@ ScriptOriginOptions OriginOptionsForEval(
       is_opaque = true;
     }
   }
-  recordreplay::Assert("ScriptOriginOptions OriginOptionsForEval %d",
+  recordreplay::Print("ScriptOriginOptions OriginOptionsForEval %d",
                        is_shared_cross_origin);
   return ScriptOriginOptions(is_shared_cross_origin, is_opaque);
 }
diff --git a/src/objects/script-inl.h b/src/objects/script-inl.h
index 695838da5859..417d6b9cb21a 100644
--- a/src/objects/script-inl.h
+++ b/src/objects/script-inl.h
@@ -155,7 +155,7 @@ void Script::set_is_repl_mode(bool value) {
 }
 
 ScriptOriginOptions Script::origin_options() {
-  recordreplay::Assert("ScriptOriginOptions Script::origin_options %d",
+  recordreplay::Print("ScriptOriginOptions Script::origin_options %d",
                        OriginOptionsBits::decode(flags()));
   return ScriptOriginOptions(OriginOptionsBits::decode(flags()));
 }

From c5ecace9a9d38b7dfdc0fefabbda332bf3fd3d1e Mon Sep 17 00:00:00 2001
From: "D. Seifert" <Domiii@users.noreply.github.com>
Date: Wed, 16 Apr 2025 21:21:49 +0800
Subject: [PATCH 06/20] Assert ComputeLocation

---
 src/execution/isolate.cc      | 10 ++++++++++
 src/objects/call-site-info.cc |  4 ++++
 2 files changed, 14 insertions(+)

diff --git a/src/execution/isolate.cc b/src/execution/isolate.cc
index 60246e2e78c2..946f06e52964 100644
--- a/src/execution/isolate.cc
+++ b/src/execution/isolate.cc
@@ -2570,6 +2570,9 @@ bool Isolate::ComputeLocation(MessageLocation* target) {
 
   if (summary.IsJavaScript()) {
     shared = handle(summary.AsJavaScript().function()->shared(), this);
+    recordreplay::AssertMaybeEventsDisallowed(
+      "[PRO-1150] Isolate::ComputeLocation %d",
+      Handle<Script>::cast(script)->id());
   }
   if (summary.AreSourcePositionsAvailable()) {
     int pos = summary.SourcePosition();
@@ -2604,6 +2607,9 @@ bool Isolate::ComputeLocationFromException(MessageLocation* target,
   if (!script->IsScript()) return false;
 
   Handle<Script> cast_script(Script::cast(*script), this);
+
+  recordreplay::AssertMaybeEventsDisallowed("[PRO-1150] Isolate::ComputeLocationFromException %d", cast_script->id());
+
   *target = MessageLocation(cast_script, start_pos_value, end_pos_value);
   return true;
 }
@@ -2639,6 +2645,10 @@ bool Isolate::ComputeLocationFromDetailedStackTrace(MessageLocation* target,
                               this);
   const int pos = StackFrameInfo::GetSourcePosition(info);
   *target = MessageLocation(handle(info->script(), this), pos, pos + 1);
+  
+  recordreplay::AssertMaybeEventsDisallowed(
+    "[PRO-1150] Isolate::ComputeLocationFromDetailedStackTrace %d",
+    info->script().id());
   return true;
 }
 
diff --git a/src/objects/call-site-info.cc b/src/objects/call-site-info.cc
index 4b57bcbfdf48..c70918989892 100644
--- a/src/objects/call-site-info.cc
+++ b/src/objects/call-site-info.cc
@@ -553,6 +553,10 @@ bool CallSiteInfo::ComputeLocation(Handle<CallSiteInfo> info,
   if (!shared->IsSubjectToDebugging()) return false;
   Handle<Script> script(Script::cast(shared->script()), isolate);
   if (script->source().IsUndefined()) return false;
+  
+  recordreplay::AssertMaybeEventsDisallowed(
+    "[PRO-1150] CallSiteInfo::ComputeLocation %d",
+    script->id());
   if (info->flags() & kIsSourcePositionComputed ||
       (shared->HasBytecodeArray() &&
        shared->GetBytecodeArray(isolate).HasSourcePositionTable())) {

From df7e6cd44fc510777aebc372421380f0189a2cd8 Mon Sep 17 00:00:00 2001
From: "D. Seifert" <Domiii@users.noreply.github.com>
Date: Thu, 17 Apr 2025 19:05:59 +0800
Subject: [PATCH 07/20] improve MessageLocation asserts

---
 src/execution/isolate.cc  |  7 ++-----
 src/execution/messages.cc | 23 +++++++++++++++++++----
 2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/src/execution/isolate.cc b/src/execution/isolate.cc
index 946f06e52964..872db7492468 100644
--- a/src/execution/isolate.cc
+++ b/src/execution/isolate.cc
@@ -2570,9 +2570,6 @@ bool Isolate::ComputeLocation(MessageLocation* target) {
 
   if (summary.IsJavaScript()) {
     shared = handle(summary.AsJavaScript().function()->shared(), this);
-    recordreplay::AssertMaybeEventsDisallowed(
-      "[PRO-1150] Isolate::ComputeLocation %d",
-      Handle<Script>::cast(script)->id());
   }
   if (summary.AreSourcePositionsAvailable()) {
     int pos = summary.SourcePosition();
@@ -2647,8 +2644,8 @@ bool Isolate::ComputeLocationFromDetailedStackTrace(MessageLocation* target,
   *target = MessageLocation(handle(info->script(), this), pos, pos + 1);
   
   recordreplay::AssertMaybeEventsDisallowed(
-    "[PRO-1150] Isolate::ComputeLocationFromDetailedStackTrace %d",
-    info->script().id());
+    "[PRO-1150] Isolate::ComputeLocationFromDetailedStackTrace %d %d",
+    info->script().id(), pos);
   return true;
 }
 
diff --git a/src/execution/messages.cc b/src/execution/messages.cc
index 8bd6fe99a3df..bb9b43e788db 100644
--- a/src/execution/messages.cc
+++ b/src/execution/messages.cc
@@ -32,7 +32,11 @@ MessageLocation::MessageLocation(Handle<Script> script, int start_pos,
     : script_(script),
       start_pos_(start_pos),
       end_pos_(end_pos),
-      bytecode_offset_(-1) {}
+      bytecode_offset_(-1) {
+  recordreplay::AssertMaybeEventsDisallowed(
+    "[PRO-1150] MessageLocation::MessageLocation A %d %d %d",
+    script->id(), start_pos, end_pos);
+}
 
 MessageLocation::MessageLocation(Handle<Script> script, int start_pos,
                                  int end_pos, Handle<SharedFunctionInfo> shared)
@@ -40,7 +44,11 @@ MessageLocation::MessageLocation(Handle<Script> script, int start_pos,
       start_pos_(start_pos),
       end_pos_(end_pos),
       bytecode_offset_(-1),
-      shared_(shared) {}
+      shared_(shared) {        
+  recordreplay::AssertMaybeEventsDisallowed(
+    "[PRO-1150] MessageLocation::MessageLocation B %d %d %d",
+    script->id(), start_pos, end_pos);
+}
 
 MessageLocation::MessageLocation(Handle<Script> script,
                                  Handle<SharedFunctionInfo> shared,
@@ -49,10 +57,17 @@ MessageLocation::MessageLocation(Handle<Script> script,
       start_pos_(-1),
       end_pos_(-1),
       bytecode_offset_(bytecode_offset),
-      shared_(shared) {}
+      shared_(shared) {
+  recordreplay::AssertMaybeEventsDisallowed(
+    "[PRO-1150] MessageLocation::MessageLocation C %d",
+    script->id());
+}
 
 MessageLocation::MessageLocation()
-    : start_pos_(-1), end_pos_(-1), bytecode_offset_(-1) {}
+    : start_pos_(-1), end_pos_(-1), bytecode_offset_(-1) {
+  recordreplay::AssertMaybeEventsDisallowed(
+    "[PRO-1150] MessageLocation::MessageLocation D");
+}
 
 // If no message listeners have been registered this one is called
 // by default.

From 18ba61a2eeb4830dc830b78e8c3dac02d1869f2f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Thu, 17 Apr 2025 14:33:24 +0200
Subject: [PATCH 08/20] replay `ErrorUtils::FormatStackTrace`

---
 src/execution/messages.cc | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/execution/messages.cc b/src/execution/messages.cc
index bb9b43e788db..b926a8a0d558 100644
--- a/src/execution/messages.cc
+++ b/src/execution/messages.cc
@@ -33,7 +33,7 @@ MessageLocation::MessageLocation(Handle<Script> script, int start_pos,
       start_pos_(start_pos),
       end_pos_(end_pos),
       bytecode_offset_(-1) {
-  recordreplay::AssertMaybeEventsDisallowed(
+  recordreplay::Print(
     "[PRO-1150] MessageLocation::MessageLocation A %d %d %d",
     script->id(), start_pos, end_pos);
 }
@@ -44,8 +44,8 @@ MessageLocation::MessageLocation(Handle<Script> script, int start_pos,
       start_pos_(start_pos),
       end_pos_(end_pos),
       bytecode_offset_(-1),
-      shared_(shared) {        
-  recordreplay::AssertMaybeEventsDisallowed(
+      shared_(shared) {
+  recordreplay::Print(
     "[PRO-1150] MessageLocation::MessageLocation B %d %d %d",
     script->id(), start_pos, end_pos);
 }
@@ -58,14 +58,14 @@ MessageLocation::MessageLocation(Handle<Script> script,
       end_pos_(-1),
       bytecode_offset_(bytecode_offset),
       shared_(shared) {
-  recordreplay::AssertMaybeEventsDisallowed(
+  recordreplay::Print(
     "[PRO-1150] MessageLocation::MessageLocation C %d",
     script->id());
 }
 
 MessageLocation::MessageLocation()
     : start_pos_(-1), end_pos_(-1), bytecode_offset_(-1) {
-  recordreplay::AssertMaybeEventsDisallowed(
+  recordreplay::Print(
     "[PRO-1150] MessageLocation::MessageLocation D");
 }
 
@@ -453,7 +453,14 @@ MaybeHandle<Object> ErrorUtils::FormatStackTrace(Isolate* isolate,
     }
   }
 
-  return builder.Finish();
+  MaybeHandle<String> rv = builder.Finish();
+  if (recordreplay::IsRecordingOrReplaying("ErrorUtils::FormatStackTrace")) {
+    // [PRO-1150] Replay error stack.
+    std::string str = rv.ToHandleChecked()->ToCString().get();
+    recordreplay::RecordReplayString("ErrorUtils::FormatStackTrace", str);
+    rv = isolate->factory()->NewStringFromUtf8(base::CStrVector(str.c_str()));
+  }
+  return rv;
 }
 
 Handle<String> MessageFormatter::Format(Isolate* isolate, MessageTemplate index,

From 36a00dcf022ee0280e9e78e332887b925083c1e2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Thu, 17 Apr 2025 14:43:37 +0200
Subject: [PATCH 09/20] bring back (tweaked) early return in
 `RecordReplayOnExceptionUnwind`

---
 src/api/api.cc | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/src/api/api.cc b/src/api/api.cc
index f3277d19610c..c9ff03041c33 100644
--- a/src/api/api.cc
+++ b/src/api/api.cc
@@ -10969,6 +10969,37 @@ void RecordReplayOnExceptionUnwind(Isolate* isolate) {
   if (!isolate->is_catchable_by_javascript(*exception))
     return;
 
+  {
+    // Note: Most of this is copied from |ComputeLocation| in messages.cc.
+    JavaScriptFrameIterator it(isolate);
+    if (!it.done()) {
+      // Compute the location from the function and the relocation info of the
+      // baseline code. For optimized code this will use the deoptimization
+      // information to get canonical location information.
+      std::vector<FrameSummary> frames;
+      it.frame()->Summarize(&frames);
+      if (!frames.empty()) { // There might not always be a frame due to RUN-1920.
+        bool hasFrameFromRegisteredScript = false;
+        for (int i = static_cast<int>(frames.size()) - 1; i >= 0; i--) {
+          auto& summary = *frames[i].AsJavaScript();
+          Handle<SharedFunctionInfo> shared(summary.function()->shared(), isolate);
+          Handle<Object> script(shared->script(), isolate);
+          if (script->IsScript()) {
+            Handle<Script> casted_script = Handle<Script>::cast(script);
+            if (!RecordReplayHasRegisteredScript(*casted_script)) {
+              hasFrameFromRegisteredScript = true;
+              break;
+            }
+          }
+        }
+        if (!hasFrameFromRegisteredScript) {
+          // Don't report errors from unregistered.
+          return;
+        }
+      }
+    }
+  }
+
   isolate->clear_pending_exception();
   Handle<Object> message(isolate->pending_message(), isolate);
   isolate->clear_pending_message();

From 28b695e384b246dabd016daca03ea3f8bb132e23 Mon Sep 17 00:00:00 2001
From: "D. Seifert" <Domiii@users.noreply.github.com>
Date: Thu, 17 Apr 2025 20:49:34 +0800
Subject: [PATCH 10/20] replay GetTopValidFrame

---
 src/execution/frames.cc  | 9 +++++++++
 src/execution/isolate.cc | 2 --
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/execution/frames.cc b/src/execution/frames.cc
index 5d613e69705e..c6a4f80cb6aa 100644
--- a/src/execution/frames.cc
+++ b/src/execution/frames.cc
@@ -249,6 +249,8 @@ int StackTraceFrameIterator::FrameFunctionCount() const {
   return static_cast<int>(infos.size());
 }
 
+extern bool RecordReplayHasRegisteredScript(Script script);
+
 FrameSummary StackTraceFrameIterator::GetTopValidFrame() const {
   DCHECK(!done());
   // Like FrameSummary::GetTop, but additionally observes
@@ -258,6 +260,13 @@ FrameSummary StackTraceFrameIterator::GetTopValidFrame() const {
   if (is_javascript()) {
     for (int i = static_cast<int>(frames.size()) - 1; i >= 0; i--) {
       if (!IsValidJSFunction(*frames[i].AsJavaScript().function())) continue;
+      if (recordreplay::IsRecordingOrReplaying("StackTraceFrameIterator::GetTopValidFrame") &&
+        !recordreplay::AreEventsDisallowed()) {
+        // [PRO-1105] Skip our own (or generally, divergent) scripts.
+        if (!RecordReplayHasRegisteredScript(*Handle<Script>::cast(frames[i].script()))) {
+          continue;
+        }
+      }
       return frames[i];
     }
     UNREACHABLE();
diff --git a/src/execution/isolate.cc b/src/execution/isolate.cc
index 872db7492468..78a436c4ce13 100644
--- a/src/execution/isolate.cc
+++ b/src/execution/isolate.cc
@@ -2605,8 +2605,6 @@ bool Isolate::ComputeLocationFromException(MessageLocation* target,
 
   Handle<Script> cast_script(Script::cast(*script), this);
 
-  recordreplay::AssertMaybeEventsDisallowed("[PRO-1150] Isolate::ComputeLocationFromException %d", cast_script->id());
-
   *target = MessageLocation(cast_script, start_pos_value, end_pos_value);
   return true;
 }

From 960e40e939c05ec32d419d07af095e2d77122621 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Thu, 17 Apr 2025 14:56:33 +0200
Subject: [PATCH 11/20] fix compilation error

---
 src/api/api.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/api/api.cc b/src/api/api.cc
index c9ff03041c33..9096e253de78 100644
--- a/src/api/api.cc
+++ b/src/api/api.cc
@@ -10981,7 +10981,7 @@ void RecordReplayOnExceptionUnwind(Isolate* isolate) {
       if (!frames.empty()) { // There might not always be a frame due to RUN-1920.
         bool hasFrameFromRegisteredScript = false;
         for (int i = static_cast<int>(frames.size()) - 1; i >= 0; i--) {
-          auto& summary = *frames[i].AsJavaScript();
+          auto& summary = frames[i].AsJavaScript();
           Handle<SharedFunctionInfo> shared(summary.function()->shared(), isolate);
           Handle<Object> script(shared->script(), isolate);
           if (script->IsScript()) {

From 11bd9678f93a77cd5b3e2bff68a65c6b33ba4f0c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Thu, 17 Apr 2025 16:36:18 +0200
Subject: [PATCH 12/20] add print

---
 src/execution/frames.cc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/execution/frames.cc b/src/execution/frames.cc
index c6a4f80cb6aa..c407462561d1 100644
--- a/src/execution/frames.cc
+++ b/src/execution/frames.cc
@@ -258,14 +258,18 @@ FrameSummary StackTraceFrameIterator::GetTopValidFrame() const {
   std::vector<FrameSummary> frames;
   frame()->Summarize(&frames);
   if (is_javascript()) {
+    recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame size %d", static_cast<int>(frames.size()));
     for (int i = static_cast<int>(frames.size()) - 1; i >= 0; i--) {
       if (!IsValidJSFunction(*frames[i].AsJavaScript().function())) continue;
+      recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame 1")
       if (recordreplay::IsRecordingOrReplaying("StackTraceFrameIterator::GetTopValidFrame") &&
         !recordreplay::AreEventsDisallowed()) {
         // [PRO-1105] Skip our own (or generally, divergent) scripts.
         if (!RecordReplayHasRegisteredScript(*Handle<Script>::cast(frames[i].script()))) {
+          recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame i %d script_id %d continue", i, frames[i].script()->id());
           continue;
         }
+        recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame i %d script_id %d return", i, frames[i].script()->id());
       }
       return frames[i];
     }

From f36fc1dedde9c178485b7357e5e5bf1453503749 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Thu, 17 Apr 2025 16:45:10 +0200
Subject: [PATCH 13/20] fix compile

---
 src/execution/frames.cc | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/execution/frames.cc b/src/execution/frames.cc
index c407462561d1..ca8f6d1c5c25 100644
--- a/src/execution/frames.cc
+++ b/src/execution/frames.cc
@@ -261,15 +261,15 @@ FrameSummary StackTraceFrameIterator::GetTopValidFrame() const {
     recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame size %d", static_cast<int>(frames.size()));
     for (int i = static_cast<int>(frames.size()) - 1; i >= 0; i--) {
       if (!IsValidJSFunction(*frames[i].AsJavaScript().function())) continue;
-      recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame 1")
+      recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame 1");
       if (recordreplay::IsRecordingOrReplaying("StackTraceFrameIterator::GetTopValidFrame") &&
         !recordreplay::AreEventsDisallowed()) {
         // [PRO-1105] Skip our own (or generally, divergent) scripts.
         if (!RecordReplayHasRegisteredScript(*Handle<Script>::cast(frames[i].script()))) {
-          recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame i %d script_id %d continue", i, frames[i].script()->id());
+          recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame i %d script_id %d continue", i, *Handle<Script>::cast(frames[i].script()))->id());
           continue;
         }
-        recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame i %d script_id %d return", i, frames[i].script()->id());
+        recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame i %d script_id %d return", i, *Handle<Script>::cast(frames[i].script()))->id());
       }
       return frames[i];
     }

From fd0ab8a5d56d4170420163a5c0c41b3564695adb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Thu, 17 Apr 2025 16:52:53 +0200
Subject: [PATCH 14/20] fix compile maybe

---
 src/execution/frames.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/execution/frames.cc b/src/execution/frames.cc
index ca8f6d1c5c25..229eebfea32c 100644
--- a/src/execution/frames.cc
+++ b/src/execution/frames.cc
@@ -266,10 +266,10 @@ FrameSummary StackTraceFrameIterator::GetTopValidFrame() const {
         !recordreplay::AreEventsDisallowed()) {
         // [PRO-1105] Skip our own (or generally, divergent) scripts.
         if (!RecordReplayHasRegisteredScript(*Handle<Script>::cast(frames[i].script()))) {
-          recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame i %d script_id %d continue", i, *Handle<Script>::cast(frames[i].script()))->id());
+          recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame i %d script_id %d continue", i, Handle<Script>::cast(frames[i].script())->id());
           continue;
         }
-        recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame i %d script_id %d return", i, *Handle<Script>::cast(frames[i].script()))->id());
+        recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame i %d script_id %d return", i, Handle<Script>::cast(frames[i].script())->id());
       }
       return frames[i];
     }

From f025f756f6c0f4a778af5e6a0fed7515866700c4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Thu, 17 Apr 2025 17:17:11 +0200
Subject: [PATCH 15/20] return first unregistered as fallback

---
 src/execution/frames.cc | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/execution/frames.cc b/src/execution/frames.cc
index 229eebfea32c..78ee0b6bf0ea 100644
--- a/src/execution/frames.cc
+++ b/src/execution/frames.cc
@@ -259,6 +259,7 @@ FrameSummary StackTraceFrameIterator::GetTopValidFrame() const {
   frame()->Summarize(&frames);
   if (is_javascript()) {
     recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame size %d", static_cast<int>(frames.size()));
+    base::Optional<FrameSummary> normal_rv;
     for (int i = static_cast<int>(frames.size()) - 1; i >= 0; i--) {
       if (!IsValidJSFunction(*frames[i].AsJavaScript().function())) continue;
       recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame 1");
@@ -267,12 +268,20 @@ FrameSummary StackTraceFrameIterator::GetTopValidFrame() const {
         // [PRO-1105] Skip our own (or generally, divergent) scripts.
         if (!RecordReplayHasRegisteredScript(*Handle<Script>::cast(frames[i].script()))) {
           recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame i %d script_id %d continue", i, Handle<Script>::cast(frames[i].script())->id());
+          if (!fallback_unregistered.has_value()) {
+            normal_rv = frames[i];
+          }
           continue;
         }
         recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame i %d script_id %d return", i, Handle<Script>::cast(frames[i].script())->id());
       }
       return frames[i];
     }
+    if (normal_rv.has_value()) {
+      // if all frames belongs to unregistered scripts return the first one like that
+      recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame returning fallback unregistered frame");
+      return *normal_rv;
+    }
     UNREACHABLE();
   }
 #if V8_ENABLE_WEBASSEMBLY

From 6ea087aeb8a5f5ffc3c197c9aefb6cdcac4d6a0b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Thu, 17 Apr 2025 17:24:51 +0200
Subject: [PATCH 16/20] second time is a charm

---
 src/execution/frames.cc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/execution/frames.cc b/src/execution/frames.cc
index 78ee0b6bf0ea..f2508f308c5b 100644
--- a/src/execution/frames.cc
+++ b/src/execution/frames.cc
@@ -268,8 +268,8 @@ FrameSummary StackTraceFrameIterator::GetTopValidFrame() const {
         // [PRO-1105] Skip our own (or generally, divergent) scripts.
         if (!RecordReplayHasRegisteredScript(*Handle<Script>::cast(frames[i].script()))) {
           recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame i %d script_id %d continue", i, Handle<Script>::cast(frames[i].script())->id());
-          if (!fallback_unregistered.has_value()) {
-            normal_rv = frames[i];
+          if (!normal_rv.has_value()) {
+            normal_rv.emplace(std::move(frames[i]));
           }
           continue;
         }

From eba7153d67acf16c035efc96ed2dd249aebae460 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Thu, 17 Apr 2025 18:34:48 +0200
Subject: [PATCH 17/20] add somewhat random prints

---
 src/api/api.cc                  | 5 +++++
 src/runtime/runtime-internal.cc | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/src/api/api.cc b/src/api/api.cc
index 9096e253de78..9238d839dfb3 100644
--- a/src/api/api.cc
+++ b/src/api/api.cc
@@ -10966,6 +10966,7 @@ void RecordReplayOnExceptionUnwind(Isolate* isolate) {
     return;
 
   Handle<Object> exception(isolate->pending_exception(), isolate);
+  recordreplay::Print("[PRO-1150] RecordReplayOnExceptionUnwind A %d", isolate->is_catchable_by_javascript(*exception));
   if (!isolate->is_catchable_by_javascript(*exception))
     return;
 
@@ -11000,10 +11001,13 @@ void RecordReplayOnExceptionUnwind(Isolate* isolate) {
     }
   }
 
+  recordreplay::Print("[PRO-1150] RecordReplayOnExceptionUnwind B");
+
   isolate->clear_pending_exception();
   Handle<Object> message(isolate->pending_message(), isolate);
   isolate->clear_pending_message();
   Handle<Object> scheduledException;
+  recordreplay::Print("[PRO-1150] RecordReplayOnExceptionUnwind C %d", isolate->has_scheduled_exception());
   if (isolate->has_scheduled_exception()) {
     scheduledException = Handle<Object>(isolate->scheduled_exception(), isolate);
     isolate->clear_scheduled_exception();
@@ -11016,6 +11020,7 @@ void RecordReplayOnExceptionUnwind(Isolate* isolate) {
   CHECK(!isolate->has_pending_exception());
   isolate->set_pending_exception(*exception);
   isolate->set_pending_message(*message);
+  recordreplay::Print("[PRO-1150] RecordReplayOnExceptionUnwind D %d", scheduledException.is_null());
   if (!scheduledException.is_null()) {
     isolate->set_scheduled_exception(*scheduledException);
   }
diff --git a/src/runtime/runtime-internal.cc b/src/runtime/runtime-internal.cc
index 92eb39d9aa97..1ddaa51b6194 100644
--- a/src/runtime/runtime-internal.cc
+++ b/src/runtime/runtime-internal.cc
@@ -195,6 +195,10 @@ RUNTIME_FUNCTION(Runtime_UnwindAndFindExceptionHandler) {
   // a script, try/catch block, or try/finally block. If the progress counter
   // when unwinding is the same as the last time when unwinding, this is a
   // frame unwind instead of an initial throw and we can ignore it.
+  recordreplay::Print(
+      "[PRO-1150] Runtime_UnwindAndFindExceptionHandler %d %d %d\n",
+      *gProgressCounter, gLastExceptionUnwindProgress,
+      recordreplay::AreEventsDisallowed());
   if (recordreplay::IsRecordingOrReplaying() &&
       !recordreplay::AreEventsDisallowed() &&
       IsMainThread() &&

From 6670ae52c1ce6d3ae8cf4c0e43b81ceb1d5cb71e Mon Sep 17 00:00:00 2001
From: "D. Seifert" <Domiii@users.noreply.github.com>
Date: Fri, 18 Apr 2025 19:01:14 +0800
Subject: [PATCH 18/20] add assert

---
 src/api/api.cc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/api/api.cc b/src/api/api.cc
index c9ff03041c33..4dbecd26e6eb 100644
--- a/src/api/api.cc
+++ b/src/api/api.cc
@@ -10986,6 +10986,10 @@ void RecordReplayOnExceptionUnwind(Isolate* isolate) {
           Handle<Object> script(shared->script(), isolate);
           if (script->IsScript()) {
             Handle<Script> casted_script = Handle<Script>::cast(script);
+            recordreplay::Assert("[PRO-1105] RecordReplayOnExceptionUnwind casted_script %d/%d id=%d",
+                                 i,
+                                 static_cast<int>(frames.size()),
+                                 casted_script->id());
             if (!RecordReplayHasRegisteredScript(*casted_script)) {
               hasFrameFromRegisteredScript = true;
               break;

From 04097c48b35b35fdb4229868c927a9b455a6f93e Mon Sep 17 00:00:00 2001
From: "D. Seifert" <Domiii@users.noreply.github.com>
Date: Fri, 18 Apr 2025 19:51:49 +0800
Subject: [PATCH 19/20] diagnostics

---
 src/api/api.cc | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/src/api/api.cc b/src/api/api.cc
index 2e475fd71fa7..72564037c612 100644
--- a/src/api/api.cc
+++ b/src/api/api.cc
@@ -10982,16 +10982,22 @@ void RecordReplayOnExceptionUnwind(Isolate* isolate) {
       if (!frames.empty()) { // There might not always be a frame due to RUN-1920.
         bool hasFrameFromRegisteredScript = false;
         for (int i = static_cast<int>(frames.size()) - 1; i >= 0; i--) {
-          auto& summary = frames[i].AsJavaScript();
+          FrameSummary::JavaScriptFrameSummary const& summary = frames[i].AsJavaScript();
           Handle<SharedFunctionInfo> shared(summary.function()->shared(), isolate);
-          Handle<Object> script(shared->script(), isolate);
-          if (script->IsScript()) {
-            Handle<Script> casted_script = Handle<Script>::cast(script);
-            recordreplay::Assert("[PRO-1105] RecordReplayOnExceptionUnwind casted_script %d/%d id=%d",
+          Handle<Object> s(shared->script(), isolate);
+          if (s->IsScript()) {
+            Handle<Script> script = Handle<Script>::cast(s);
+
+            std::string script_name = script->name().IsString()
+              ? String::cast(script->name()).ToCString().get()
+              : "(anonymous script)";
+            recordreplay::Assert("[PRO-1105] RecordReplayOnExceptionUnwind %d/%d id=%d fun=%s script=%s",
                                  i,
                                  static_cast<int>(frames.size()),
-                                 casted_script->id());
-            if (!RecordReplayHasRegisteredScript(*casted_script)) {
+                                 script->id(),
+                                 SharedFunctionInfo::DebugName(shared),
+                                 script_name.c_str());
+            if (!RecordReplayHasRegisteredScript(*script)) {
               hasFrameFromRegisteredScript = true;
               break;
             }

From dd0b5a315bab8e519379998172b7f316d7f5b299 Mon Sep 17 00:00:00 2001
From: "D. Seifert" <Domiii@users.noreply.github.com>
Date: Fri, 18 Apr 2025 20:34:05 +0800
Subject: [PATCH 20/20] diagnostics

---
 src/execution/frames.cc | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/execution/frames.cc b/src/execution/frames.cc
index f2508f308c5b..74ae94721273 100644
--- a/src/execution/frames.cc
+++ b/src/execution/frames.cc
@@ -250,6 +250,7 @@ int StackTraceFrameIterator::FrameFunctionCount() const {
 }
 
 extern bool RecordReplayHasRegisteredScript(Script script);
+extern "C" void V8RecordReplayGetCurrentJSStack(std::string* js_stack);
 
 FrameSummary StackTraceFrameIterator::GetTopValidFrame() const {
   DCHECK(!done());
@@ -258,7 +259,12 @@ FrameSummary StackTraceFrameIterator::GetTopValidFrame() const {
   std::vector<FrameSummary> frames;
   frame()->Summarize(&frames);
   if (is_javascript()) {
-    recordreplay::Print("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame size %d", static_cast<int>(frames.size()));
+    
+    std::string js_stack;
+    V8RecordReplayGetCurrentJSStack(&js_stack);
+    recordreplay::Trace("[PRO-1150] StackTraceFrameIterator::GetTopValidFrame size %d %s",
+                        static_cast<int>(frames.size()),
+                        js_stack.c_str());
     base::Optional<FrameSummary> normal_rv;
     for (int i = static_cast<int>(frames.size()) - 1; i >= 0; i--) {
       if (!IsValidJSFunction(*frames[i].AsJavaScript().function())) continue;