searchSkills() called .trim() on query without null-guard. When
DiscoverSkills is invoked through ExecuteExtraTool with missing
description, query is undefined, causing 'Cannot read properties of
undefined (reading trim)'.
Fixed with optional chaining: !query.trim() → !query?.trim()
Co-Authored-By: deepseek-v4-pro <deepseek-ai@claude-code-best.win>