Fix parsing incomplete appmanifest files

Incomplete appmanifest files can apparently be left over from old
installations. Ignore such files and print a warning.

Fixes #273

CHANGELOG.md

@@ -7,6 +7,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ## [Unreleased]
 ### Fixed
  - Fix Protontricks crash when custom Proton has an empty `compatibilitytool.vdf` manifest
+ - Fix Protontricks crash when an incomplete appmanifest file is parsed
 
 ## [1.11.0] - 2023-12-30
 ### Added

src/protontricks/steam.py

@@ -241,8 +241,16 @@ def from_appmanifest(cls, path, steam_lib_paths, steam_path=None):
         try:
             name = app_state["name"]
         except KeyError:
-            # Older app installations also use `userconfig/name`
-            name = app_state["userconfig"]["name"]
+            try:
+                # Older app installations also use `userconfig/name`
+                name = app_state["userconfig"]["name"]
+            except KeyError:
+                logger.warning(
+                    "Incomplete appmanifest found at %s. This might be a "
+                    "leftover file from an old installation. Skipping...",
+                    path
+                )
+                return None
 
         # Proton prefix may exist on a different library
         prefix_path = find_appid_proton_prefix(

tests/test_steam.py

@@ -84,6 +84,40 @@ def test_steam_app_from_appmanifest_empty(self, steam_app_factory):
         """
         steam_app = steam_app_factory(name="Fake game", appid=10)
 
+        appmanifest_path = \
+            Path(steam_app.install_path).parent.parent / "appmanifest_10.acf"
+        appmanifest_path.write_text(
+            vdf.dumps({
+                "AppState": {
+                    "appid": "10",
+                    "Universe": "1",
+                    "installdir": "Fake game",
+                    # Use the same StateFlags mentioned in the #273 issue.
+                    # Two flags set here are `StateUpdateRequired` and
+                    # `StateUpdateStarted`, which might indicate the file
+                    # is not properly tracked by Steam itself, since the
+                    # installation directory was gone at this point.
+                    "StateFlags": "1026"
+                }
+            })
+        )
+
+        # Incomplete appmanifest file is ignored
+        assert not SteamApp.from_appmanifest(
+            path=appmanifest_path,
+            steam_lib_paths=[]
+        )
+
+    def test_steam_app_from_appmanifest_incomplete(self, steam_app_factory):
+        """
+        Try to deserialize from an incomplete appmanifest and check that no
+        SteamApp is returned.
+
+        Incomplete appmanifests can supposedly be created when moving app
+        installations
+        """
+        steam_app = steam_app_factory(name="Fake game", appid=10)
+
         appmanifest_path = \
             Path(steam_app.install_path).parent.parent / "appmanifest_10.acf"
         appmanifest_path.write_text("")