correctly handle raised exception inside function calls

.changeset/lazy-rabbits-confess.md

@@ -0,0 +1,5 @@
+---
+"livekit-agents": patch
+---
+
+handles error in function calls

examples/voice-pipeline-agent/function_calling_weather.py

@@ -42,7 +42,9 @@ async def get_weather(
                     # response from the function call is returned to the LLM
                     return f"The weather in {location} is {weather_data}."
                 else:
-                    raise f"Failed to get weather data, status code: {response.status}"
+                    raise Exception(
+                        f"Failed to get weather data, status code: {response.status}"
+                    )
 
 
 def prewarm_process(proc: JobProcess):

livekit-agents/livekit/agents/pipeline/pipeline_agent.py

@@ -779,7 +779,7 @@ def _commit_user_question_if_needed() -> None:
 
                 for called_fnc in called_fncs:
                     # ignore the function calls that returns None
-                    if called_fnc.result is None:
+                    if called_fnc.result is None and called_fnc.exception is None:
                         continue
 
                     tool_calls_info.append(called_fnc.call_info)

tests/test_llm.py

@@ -145,6 +145,25 @@ async def test_basic_fnc_calls(llm_factory: Callable[[], llm.LLM]):
     assert len(calls) == 2, "get_weather should be called twice"
 
 
+@pytest.mark.parametrize("llm_factory", LLMS)
+async def test_function_call_exception_handling(llm_factory: Callable[[], llm.LLM]):
+    input_llm = llm_factory()
+    fnc_ctx = FncCtx()
+
+    @fnc_ctx.ai_callable(description="Simulate a failure")
+    async def failing_function():
+        raise RuntimeError("Simulated failure")
+
+    stream = await _request_fnc_call(input_llm, "Call the failing function", fnc_ctx)
+    calls = stream.execute_functions()
+    await asyncio.gather(*[f.task for f in calls], return_exceptions=True)
+    await stream.aclose()
+
+    assert len(calls) == 1
+    assert isinstance(calls[0].exception, RuntimeError)
+    assert str(calls[0].exception) == "Simulated failure"
+
+
 @pytest.mark.parametrize("llm_factory", LLMS)
 async def test_runtime_addition(llm_factory: Callable[[], llm.LLM]):
     input_llm = llm_factory()