[Bug]:'str' object has no attribute 'output'

### What happened?

Using the usage example provided in read.me, an error is displayed: 'str' object has no attribute 'output'. The following is the trajectory file. Could you please tell me what the problem is and how to solve it? Could any expert help solve it? Thank you!!!
agents:
trae_agent:
enable_lakeview: true
model: trae_agent_model
max_steps: 200
tools:
- bash
- str_replace_based_edit_tool
- sequentialthinking
- task_done
allow_mcp_servers:
- playwright
mcp_servers:
playwright:
command: npx
args:
- "@playwright/mcp@0.0.27"
lakeview:
model: lakeview_model

models:
trae_agent_model:
model_provider: openai
model: gpt-4
max_tokens: 4096
temperature: 0.5
top_p: 1
top_k: 0
max_retries: 10
parallel_tool_calls: true
lakeview_model:
model_provider: openai
model: gpt-4
max_tokens: 4096
temperature: 0.5
top_p: 1
top_k: 0
max_retries: 10
parallel_tool_calls: true

### What did you expect to happen?

It operates normally without reporting any errors

### Traceback

_No response_

### What is your system, Python, dependency version?

_No response_

### Additional information that you believe is relevant to this bug

_No response_

Start with the README usage example and reproduce it using the supplied YAML, capturing the full traceback and Python and dependency versions. Trace the first `.output` access from that run to the responsible entry point; done means the example runs without the reported AttributeError and the case has a regression check.

Written by the indexing model from the issue text.