Bug Description

When I add register_new_step_callback=new_step_callback argument to the agent, the agent does not work and gets stuck in an endless loop.

Reproduction Steps

1. Config agent normally
2. Config agent with a simple callback with function signature def new_step_callback(state: BrowserState, model_output: AgentOutput, steps: int)

Code Sample

async def main():
    agent = Agent(
        task="go to the NYTimes and take a screenshot of the front page",
        llm=llm,
        register_new_step_callback=new_step_callback
    )
    result = await agent.run()

Version

0.1.40

LLM Model

GPT-4o

Operating System

Mac os

Relevant Log Output