fix: Raise exception when tool call result is None (#1253)

# What does this PR do?

When there are issues with the tool call function, an exception is
raised but the error message is not informative. This adds a clearer
message to tell users to check their functions.
```
Traceback (most recent call last):
  File "/Users/phayes/projects/llama-stack/llama-stack/llama_stack/distribution/server/server.py", line 208, in sse_generator
    async for item in event_gen:
  File "/Users/phayes/projects/llama-stack/llama-stack/llama_stack/providers/inline/agents/meta_reference/agents.py", line 165, in _create_agent_turn_streaming
    async for event in agent.create_and_execute_turn(request):
  File "/Users/phayes/projects/llama-stack/llama-stack/llama_stack/providers/inline/agents/meta_reference/agent_instance.py", line 197, in create_and_execute_turn
    async for chunk in self.run(
  File "/Users/phayes/projects/llama-stack/llama-stack/llama_stack/providers/inline/agents/meta_reference/agent_instance.py", line 389, in run
    async for res in self._run(
  File "/Users/phayes/projects/llama-stack/llama-stack/llama_stack/providers/inline/agents/meta_reference/agent_instance.py", line 811, in _run
    content=tool_result.content,
AttributeError: 'NoneType' object has no attribute 'content'
```

## Test Plan

Ran the same script and exception is raised with clearer error message.

Signed-off-by: Yuan Tang <terrytangyuan@gmail.com>
This commit is contained in:
Yuan Tang 2025-02-25 13:10:50 -05:00 committed by GitHub
parent 73a0c7a0e7
commit 1a044ef894
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@ -804,6 +804,10 @@ class ChatAgent(ShieldRunnerMixin):
toolgroup_args, toolgroup_args,
tool_to_group, tool_to_group,
) )
if tool_result.content is None:
raise ValueError(
f"Tool call result (id: {tool_call.call_id}, name: {tool_call.tool_name}) does not have any content"
)
result_messages = [ result_messages = [
ToolResponseMessage( ToolResponseMessage(
call_id=tool_call.call_id, call_id=tool_call.call_id,