Description

Fixes AttributeError: 'NoneType' object has no attribute 'parts' crash in GeminiLLM._parse_response() when Gemini returns a response where content is None (e.g., safety filter blocks, rate
limiting, thinking-only responses).

The existing null check in _parse_response() guarded against empty candidates but not against content itself being None. When Gemini blocks a response, response.candidates[0].content is None, so
accessing .parts on it crashes. This affected all three access points in the method (both the tools and no-tools code paths).

The fix extracts candidate and parts into guarded local variables at the top of the method, replacing three repeated unsafe access chains with a single safe extraction. Returns "" (not None) to
preserve the string-return contract shared by all other LLM providers.

Fixes #3410

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Unit Test

Added 6 new edge case tests to tests/llms/test_gemini.py:

• test_parse_response_none_content_no_tools — content=None without tools
• test_parse_response_none_content_with_tools — content=None with tools
• test_parse_response_empty_candidates — empty candidates list
• test_parse_response_none_candidates — None candidates
• test_parse_response_empty_parts_no_tools — empty parts list without tools
• test_parse_response_empty_parts_with_tools — empty parts list with tools

Run: hatch run dev_py_3_12:pytest tests/llms/test_gemini.py -v — all 8 tests pass (2 existing + 6 new).
Full suite: hatch run dev_py_3_12:pytest tests/ -v — 768 passed, 0 failures.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings

Maintainer Checklist

• closes Invalid JSON response when using memory.add with gemini-2.5-flash #3410
• Made sure Checks passed