OpenAI Codex provider crashes with "'NoneType' object is not iterable" (HTTP None)

#33932 Fixed P1 comp/agent

OpenAI Codex provider crashes with "'NoneType' object is not iterable" (HTTP None)

Switching to gpt-5.5 via the OpenAI Codex provider (subscription OAuth) crashes on the first user message with "Non-retryable error (HTTP None): 'NoneType' object is not iterable," though fallback then takes over.