Codex regression-gate finding: the OpenAI tool_calls loop dereferenced
tc.function with no null/type guard, so a persisted message.tool_calls
array containing a null or non-object entry would throw and abort artifact
collection. Mirror the existing tool_use-block guard. Adds a node-driven
regression test.
Co-authored-by: mysoul12138 <mysoul12138@users.noreply.github.com>
