Error when human message has list of dictionaries in string format

If we invoke with below way

```
messages=[HumanMessage(content='[{"key":"value"}]')]
llm.invoke(messages)
```

This would result in error

<img width="882" alt="Image" src="https://github.com/user-attachments/assets/3dae47b4-6552-4d86-aaf3-6f4d1b1e431f" />