Summary

Fixes #3011

When using the OpenAI Responses API with certain models like openai/gpt-oss-safeguard-120b, the response can contain output_text content items where the text field is null instead of a string. This causes the output_text property to raise a TypeError when accessed, as it attempts to concatenate None values.

Changes

Added a null check before appending content.text to the texts list:

# Before
if content.type == "output_text":
    texts.append(content.text)

# After  
if content.type == "output_text" and content.text:
    texts.append(content.text)

Testing

The fix ensures that when text is null, it is simply skipped rather than causing a TypeError during string concatenation.

Checklist

• Bug fix (non-breaking change which fixes an issue)
• Code follows the project's style guidelines