Fix docstring formatting and add safe check for empty message content

[mshsheikh]

Improved clarity in a multiline docstring in RunItemBase by correcting misplaced parentheses.

Also added guards in ItemHelpers.extract_last_content and extract_last_text to handle empty message.content safely and prevent potential IndexError.

[seratch]

handle empty message.content

Have you observed this pattern in real use case?

[mshsheikh]

handle empty message.content

Have you observed this pattern in real use case?

Yes @seratch , sometimes the model returns a control item with no text, so message.content can be completely empty and message.content[-1] would crash without the guard. This often happens in streaming mode when you’re piping partial results to a UI and no tokens have arrived yet.
It can also occur if the LLM makes a tool-only response or hands off right away without producing a normal message.

[seratch]

Thanks, this one should be safe to have plus it resolves potential runtime errors