Fix error message for the json schemas of non str-keyed mappings.

apischema/json_schema/schema.py

@@ -217,8 +217,8 @@ def mapping(
         with context_setter(self):
             self._ignore_first_ref = True
             key = self.visit(key_type)
-        if key["type"] != JsonType.STRING:
-            raise ValueError("Mapping types must string-convertible key")
+        if "type" not in key or key["type"] != JsonType.STRING:
+            raise ValueError("Mapping types must have string-convertible keys")
         value = self.visit(value_type)
         if "pattern" in key:
             return json_schema(

tests/integration/test_typed_dict.py → tests/integration/test_dict.py

@@ -1,4 +1,5 @@
 from datetime import date
+from typing import Any, Dict, Mapping
 
 import pytest
 
@@ -8,6 +9,20 @@
 from apischema.typing import Annotated, TypedDict
 
 
+class MyDict(dict):
+    pass
+
+
+@pytest.mark.parametrize(
+    "tp", [dict, Dict[int, Any], pytest.param(MyDict, marks=pytest.mark.xfail), Mapping]
+)
+def test_dict(tp):
+    with pytest.raises(ValueError, match="string-convertible keys"):
+        deserialization_schema(tp)
+    with pytest.raises(ValueError, match="string-convertible keys"):
+        serialization_schema(tp)
+
+
 class TD1(TypedDict, total=False):
     key1: str