[FEATURE] Support error handling for function invocation

Currently, ff-python cannot handle errors during function calls, such as the following code:

```python
def user_function(context: UserContext):
    print(1 / 0)
```

the return will be:

```
500 Internal Server Error: The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.
```