Catch type errors in dumps/dumpd (#15336)

These can happen for edge cases not covered by `default` handler (eg.
"strange" keys in dicts)

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libs/core/langchain_core/load/dump.py

@@ -17,11 +17,17 @@ def dumps(obj: Any, *, pretty: bool = False, **kwargs: Any) -> str:
     """Return a json string representation of an object."""
     if "default" in kwargs:
         raise ValueError("`default` should not be passed to dumps")
+    try:
         if pretty:
             indent = kwargs.pop("indent", 2)
             return json.dumps(obj, default=default, indent=indent, **kwargs)
         else:
             return json.dumps(obj, default=default, **kwargs)
+    except TypeError:
+        if pretty:
+            return json.dumps(to_json_not_implemented(obj), indent=indent, **kwargs)
+        else:
+            return json.dumps(to_json_not_implemented(obj), **kwargs)
 
 
 def dumpd(obj: Any) -> Dict[str, Any]:

libs/langchain/tests/unit_tests/load/test_dump.py

@@ -60,6 +60,13 @@ def test_person(snapshot: Any) -> None:
     assert Person.lc_id() == ["tests", "unit_tests", "load", "test_dump", "Person"]
 
 
+def test_typeerror() -> None:
+    assert (
+        dumps({(1, 2): 3})
+        == """{"lc": 1, "type": "not_implemented", "id": ["builtins", "dict"], "repr": "{(1, 2): 3}"}"""  # noqa: E501
+    )
+
+
 @pytest.mark.requires("openai")
 def test_serialize_openai_llm(snapshot: Any) -> None:
     llm = OpenAI(