Fixed arguments passed to InvalidTool.run(). (langchain-ai#1340)

[InvalidTool.run()](https://github.com/hwchase17/langchain/blob/72ef69d1ba33f052bf3948c1e1d7d6441b14af0a/langchain/agents/tools.py#L43) returns "{arg}is not a valid tool, try another one.". However, no function name is actually given in the argument. This causes LLM to be stuck in a loop, unable to find the right tool. This may resolve these Issues. langchain-ai#998 langchain-ai#702

Author: kurehajime

langchain/agents/agent.py

@@ -426,7 +426,7 @@ def _take_next_step(
  )
  else:
  observation = InvalidTool().run(
- output.tool_input,
+ output.tool,
  verbose=self.verbose,
  color=None,
  llm_prefix="",
@@ -473,7 +473,7 @@ async def _atake_next_step(
  )
  else:
  observation = await InvalidTool().arun(
- output.tool_input,
+ output.tool,
  verbose=self.verbose,
  color=None,
  llm_prefix="",