Avoid unwanted exception chaining when running async tool in sync context

[stevapple]

Running async tool under sync context (require settings.allow_tool_async_sync_conversion) is handled by Tool._run_async_in_sync. If there's no running event loop, we used to run the coroutine directly when handling the RuntimeError raised by asyncio.get_running_loop(). This resulted in exception chaining, where the error raised by the tool will be chained with the RuntimeError raised by asyncio. Since the result will be passed to the LM as tool call result, such behavior is regarded as unnecessary leak of implementation detail, and will diverge the result of running with async and in sync. Move the real call outside of the except block will resolve the problem.

Before

Execution error in retrieve: 
Traceback (most recent call last):
  File ".venv\Lib\site-packages\dspy\adapters\types\tool.py", line 167, in _run_async_in_sync
    loop = asyncio.get_running_loop()
RuntimeError: no running event loop

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File ".venv\Lib\site-packages\dspy\predict\react.py", line 111, in forward
    trajectory[f"observation_{idx}"] = self.tools[pred.next_tool_name](**pred.next_tool_args)
                                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
  File ".venv\Lib\site-packages\dspy\utils\callback.py", line 326, in sync_wrapper
    return fn(instance, *args, **kwargs)
  File ".venv\Lib\site-packages\dspy\adapters\types\tool.py", line 179, in __call__
    return self._run_async_in_sync(result)
           ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^
  File ".venv\Lib\site-packages\dspy\adapters\types\tool.py", line 169, in _run_async_in_sync
    return asyncio.run(coroutine)
           ~~~~~~~~~~~^^^^^^^^^^^
  File "\Lib\asyncio\runners.py", line 195, in run
    return runner.run(main)
           ~~~~~~~~~~^^^^^^
ValueError: Invalid request

After

Execution error in retrieve: 
Traceback (most recent call last):
  File ".venv\Lib\site-packages\dspy\predict\react.py", line 111, in forward
    trajectory[f"observation_{idx}"] = self.tools[pred.next_tool_name](**pred.next_tool_args)
                                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
  File ".venv\Lib\site-packages\dspy\utils\callback.py", line 326, in sync_wrapper
    return fn(instance, *args, **kwargs)
  File ".venv\Lib\site-packages\dspy\adapters\types\tool.py", line 182, in __call__
    return self._run_async_in_sync(result)
           ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^
  File ".venv\Lib\site-packages\dspy\adapters\types\tool.py", line 173, in _run_async_in_sync
    return asyncio.run(coroutine)
           ~~~~~~~~~~~^^^^^^^^^^^
  File "\Lib\asyncio\runners.py", line 195, in run
    return runner.run(main)
           ~~~~~~~~~~^^^^^^
ValueError: Invalid request

[chenmoneygithub]

Thank you for the fix!