CrewAI Sample Failing

### What happened?

```
return session_data[image_key]
~~~~~~~~~~~~^^^^^^^^^^^
TypeError: 'NoneType' object is not subscriptable
ERROR:a2a.server.apps.jsonrpc.jsonrpc_app:Request Error (ID: ce21095b-602b-4455-b171-bdfe0c3ea043): Code=-32603, Message=''NoneType' object is not subscriptable'
```

Getting this error when testing the CrewAI Sample

### Relevant log output

```shell

```

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct