core[patch]: add response kwarg to on_llm_error

# Dependencies
None

# Twitter handle
@HKydlicek

---------

Co-authored-by: Erick Friis <erick@langchain.dev>

libs/core/langchain_core/callbacks/base.py

@@ -75,7 +75,13 @@ def on_llm_error(
         parent_run_id: Optional[UUID] = None,
         **kwargs: Any,
     ) -> Any:
-        """Run when LLM errors."""
+        """Run when LLM errors.
+        Args:
+            error (BaseException): The error that occurred.
+            kwargs (Any): Additional keyword arguments.
+                - response (LLMResult): The response which was generated before
+                    the error occurred.
+        """
 
 
 class ChainManagerMixin:
@@ -351,7 +357,13 @@ async def on_llm_error(
         tags: Optional[List[str]] = None,
         **kwargs: Any,
     ) -> None:
-        """Run when LLM errors."""
+        """Run when LLM errors.
+        Args:
+            error (BaseException): The error that occurred.
+            kwargs (Any): Additional keyword arguments.
+                - response (LLMResult): The response which was generated before
+                    the error occurred.
+        """
 
     async def on_chain_start(
         self,

libs/core/langchain_core/callbacks/manager.py

@@ -623,6 +623,9 @@ def on_llm_error(
 
         Args:
             error (Exception or KeyboardInterrupt): The error.
+            kwargs (Any): Additional keyword arguments.
+                - response (LLMResult): The response which was generated before
+                    the error occurred.
         """
         handle_event(
             self.handlers,
@@ -689,6 +692,12 @@ async def on_llm_error(
 
         Args:
             error (Exception or KeyboardInterrupt): The error.
+            kwargs (Any): Additional keyword arguments.
+                - response (LLMResult): The response which was generated before
+                    the error occurred.
+
+
+
         """
         await ahandle_event(
             self.handlers,

libs/core/langchain_core/language_models/chat_models.py

@@ -223,8 +223,8 @@ def stream(
                 name=config.get("run_name"),
                 batch_size=1,
             )
+            generation: Optional[ChatGenerationChunk] = None
             try:
-                generation: Optional[ChatGenerationChunk] = None
                 for chunk in self._stream(
                     messages, stop=stop, run_manager=run_manager, **kwargs
                 ):
@@ -235,12 +235,15 @@ def stream(
                         generation += chunk
                 assert generation is not None
             except BaseException as e:
-                run_manager.on_llm_error(e)
+                run_manager.on_llm_error(
+                    e,
+                    response=LLMResult(
+                        generations=[[generation]] if generation else []
+                    ),
+                )
                 raise e
             else:
-                run_manager.on_llm_end(
-                    LLMResult(generations=[[generation]]),
-                )
+                run_manager.on_llm_end(LLMResult(generations=[[generation]]))
 
     async def astream(
         self,
@@ -277,8 +280,8 @@ async def astream(
                 name=config.get("run_name"),
                 batch_size=1,
             )
+            generation: Optional[ChatGenerationChunk] = None
             try:
-                generation: Optional[ChatGenerationChunk] = None
                 async for chunk in self._astream(
                     messages, stop=stop, run_manager=run_manager, **kwargs
                 ):
@@ -289,7 +292,12 @@ async def astream(
                         generation += chunk
                 assert generation is not None
             except BaseException as e:
-                await run_manager.on_llm_error(e)
+                await run_manager.on_llm_error(
+                    e,
+                    response=LLMResult(
+                        generations=[[generation]] if generation else []
+                    ),
+                )
                 raise e
             else:
                 await run_manager.on_llm_end(
@@ -366,7 +374,7 @@ def generate(
                 )
             except BaseException as e:
                 if run_managers:
-                    run_managers[i].on_llm_error(e)
+                    run_managers[i].on_llm_error(e, response=LLMResult(generations=[]))
                 raise e
         flattened_outputs = [
             LLMResult(generations=[res.generations], llm_output=res.llm_output)
@@ -433,7 +441,9 @@ async def agenerate(
         for i, res in enumerate(results):
             if isinstance(res, BaseException):
                 if run_managers:
-                    await run_managers[i].on_llm_error(res)
+                    await run_managers[i].on_llm_error(
+                        res, response=LLMResult(generations=[])
+                    )
                 exceptions.append(res)
         if exceptions:
             if run_managers:

libs/core/langchain_core/language_models/llms.py

@@ -384,8 +384,8 @@ def stream(
                 name=config.get("run_name"),
                 batch_size=1,
             )
+            generation: Optional[GenerationChunk] = None
             try:
-                generation: Optional[GenerationChunk] = None
                 for chunk in self._stream(
                     prompt, stop=stop, run_manager=run_manager, **kwargs
                 ):
@@ -396,7 +396,12 @@ def stream(
                         generation += chunk
                 assert generation is not None
             except BaseException as e:
-                run_manager.on_llm_error(e)
+                run_manager.on_llm_error(
+                    e,
+                    response=LLMResult(
+                        generations=[[generation]] if generation else []
+                    ),
+                )
                 raise e
             else:
                 run_manager.on_llm_end(LLMResult(generations=[[generation]]))
@@ -436,8 +441,8 @@ async def astream(
                 name=config.get("run_name"),
                 batch_size=1,
             )
+            generation: Optional[GenerationChunk] = None
             try:
-                generation: Optional[GenerationChunk] = None
                 async for chunk in self._astream(
                     prompt, stop=stop, run_manager=run_manager, **kwargs
                 ):
@@ -448,7 +453,12 @@ async def astream(
                         generation += chunk
                 assert generation is not None
             except BaseException as e:
-                await run_manager.on_llm_error(e)
+                await run_manager.on_llm_error(
+                    e,
+                    response=LLMResult(
+                        generations=[[generation]] if generation else []
+                    ),
+                )
                 raise e
             else:
                 await run_manager.on_llm_end(LLMResult(generations=[[generation]]))
@@ -539,7 +549,7 @@ def _generate_helper(
             )
         except BaseException as e:
             for run_manager in run_managers:
-                run_manager.on_llm_error(e)
+                run_manager.on_llm_error(e, response=LLMResult(generations=[]))
             raise e
         flattened_outputs = output.flatten()
         for manager, flattened_output in zip(run_managers, flattened_outputs):
@@ -707,7 +717,10 @@ async def _agenerate_helper(
             )
         except BaseException as e:
             await asyncio.gather(
-                *[run_manager.on_llm_error(e) for run_manager in run_managers]
+                *[
+                    run_manager.on_llm_error(e, response=LLMResult(generations=[]))
+                    for run_manager in run_managers
+                ]
             )
             raise e
         flattened_outputs = output.flatten()

libs/core/tests/unit_tests/fake/callbacks.py

@@ -14,6 +14,7 @@ class BaseFakeCallbackHandler(BaseModel):
     starts: int = 0
     ends: int = 0
     errors: int = 0
+    errors_args: List[Any] = []
     text: int = 0
     ignore_llm_: bool = False
     ignore_chain_: bool = False
@@ -52,8 +53,9 @@ def on_llm_end_common(self) -> None:
         self.llm_ends += 1
         self.ends += 1
 
-    def on_llm_error_common(self) -> None:
+    def on_llm_error_common(self, *args: Any, **kwargs: Any) -> None:
         self.errors += 1
+        self.errors_args.append({"args": args, "kwargs": kwargs})
 
     def on_llm_new_token_common(self) -> None:
         self.llm_streams += 1
@@ -160,7 +162,7 @@ def on_llm_error(
         *args: Any,
         **kwargs: Any,
     ) -> Any:
-        self.on_llm_error_common()
+        self.on_llm_error_common(*args, **kwargs)
 
     def on_retry(
         self,
@@ -322,7 +324,7 @@ async def on_llm_error(
         *args: Any,
         **kwargs: Any,
     ) -> None:
-        self.on_llm_error_common()
+        self.on_llm_error_common(*args, **kwargs)
 
     async def on_chain_start(
         self,

libs/core/tests/unit_tests/fake/chat_model.py

@@ -45,6 +45,7 @@ class FakeListChatModel(SimpleChatModel):
     responses: List
     sleep: Optional[float] = None
     i: int = 0
+    error_on_chunk_number: Optional[int] = None
 
     @property
     def _llm_type(self) -> str:
@@ -77,9 +78,15 @@ def _stream(
             self.i += 1
         else:
             self.i = 0
-        for c in response:
+        for i_c, c in enumerate(response):
             if self.sleep is not None:
                 time.sleep(self.sleep)
+            if (
+                self.error_on_chunk_number is not None
+                and i_c == self.error_on_chunk_number
+            ):
+                raise Exception("Fake error")
+
             yield ChatGenerationChunk(message=AIMessageChunk(content=c))
 
     async def _astream(
@@ -94,9 +101,14 @@ async def _astream(
             self.i += 1
         else:
             self.i = 0
-        for c in response:
+        for i_c, c in enumerate(response):
             if self.sleep is not None:
                 await asyncio.sleep(self.sleep)
+            if (
+                self.error_on_chunk_number is not None
+                and i_c == self.error_on_chunk_number
+            ):
+                raise Exception("Fake error")
             yield ChatGenerationChunk(message=AIMessageChunk(content=c))
 
     @property

libs/core/tests/unit_tests/fake/llm.py

@@ -60,6 +60,8 @@ def _identifying_params(self) -> Mapping[str, Any]:
 class FakeStreamingListLLM(FakeListLLM):
     """Fake streaming list LLM for testing purposes."""
 
+    error_on_chunk_number: Optional[int] = None
+
     def stream(
         self,
         input: LanguageModelInput,
@@ -69,9 +71,15 @@ def stream(
         **kwargs: Any,
     ) -> Iterator[str]:
         result = self.invoke(input, config)
-        for c in result:
+        for i_c, c in enumerate(result):
             if self.sleep is not None:
                 time.sleep(self.sleep)
+
+            if (
+                self.error_on_chunk_number is not None
+                and i_c == self.error_on_chunk_number
+            ):
+                raise Exception("Fake error")
             yield c
 
     async def astream(
@@ -83,7 +91,13 @@ async def astream(
         **kwargs: Any,
     ) -> AsyncIterator[str]:
         result = await self.ainvoke(input, config)
-        for c in result:
+        for i_c, c in enumerate(result):
             if self.sleep is not None:
                 await asyncio.sleep(self.sleep)
+
+            if (
+                self.error_on_chunk_number is not None
+                and i_c == self.error_on_chunk_number
+            ):
+                raise Exception("Fake error")
             yield c

libs/core/tests/unit_tests/language_models/chat_models/test_base.py

@@ -1,8 +1,15 @@
 """Test base chat model."""
+
 import pytest
 
 from langchain_core.messages import HumanMessage, SystemMessage
+from langchain_core.outputs.llm_result import LLMResult
 from langchain_core.tracers.context import collect_runs
+from tests.unit_tests.fake.callbacks import (
+    BaseFakeCallbackHandler,
+    FakeAsyncCallbackHandler,
+    FakeCallbackHandler,
+)
 from tests.unit_tests.fake.chat_model import FakeListChatModel
 
 
@@ -69,3 +76,33 @@ async def test_async_batch_size(messages: list, messages_2: list) -> None:
             pass
         assert len(cb.traced_runs) == 1
         assert (cb.traced_runs[0].extra or {}).get("batch_size") == 1
+
+
+async def test_stream_error_callback() -> None:
+    message = "test"
+
+    def eval_response(callback: BaseFakeCallbackHandler, i: int) -> None:
+        assert callback.errors == 1
+        assert len(callback.errors_args) == 1
+        llm_result: LLMResult = callback.errors_args[0]["kwargs"]["response"]
+        if i == 0:
+            assert llm_result.generations == []
+        else:
+            assert llm_result.generations[0][0].text == message[:i]
+
+    for i in range(0, 2):
+        llm = FakeListChatModel(
+            responses=[message],
+            error_on_chunk_number=i,
+        )
+        with pytest.raises(Exception):
+            cb_async = FakeAsyncCallbackHandler()
+            async for _ in llm.astream("Dummy message", callbacks=[cb_async]):
+                pass
+            eval_response(cb_async, i)
+
+            cb_sync = FakeCallbackHandler()
+            for _ in llm.stream("Dumy message", callbacks=[cb_sync]):
+                pass
+
+            eval_response(cb_sync, i)