From 282ad3991019fe335924b8f74a527abaf048d923 Mon Sep 17 00:00:00 2001
From: Olivier Nicole <olivier@chnik.fr>
Date: Mon, 26 Aug 2024 11:19:57 +0200
Subject: [PATCH] Improve error message

---
 lib/js_of_ocaml/json.ml | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/js_of_ocaml/json.ml b/lib/js_of_ocaml/json.ml
index 541f6fc5c2..4d9a88efc7 100644
--- a/lib/js_of_ocaml/json.ml
+++ b/lib/js_of_ocaml/json.ml
@@ -140,7 +140,10 @@ let input_reviver =
 
 let unsafe_input s =
   match Sys.backend_type with
-  | Other "wasm_of_ocaml" -> failwith "Json.unsafe_input: not implemented"
+  | Other "wasm_of_ocaml" ->
+      failwith
+        "Json.unsafe_input: not implemented (and not planned) in the Wasm backend as the \
+         inverse of `output` is not implementable"
   | _ -> json##parse_ s input_reviver
 
 class type obj = object