fix: auto-normalize array of strings in message content to openai spec

[lkapadiya-DO]

Relevant issues

Fixes an observed issue where sending an array of strings in the content block (e.g., ["what is the capital of France?"]) causes an internal AttributeError: 'str' object has no attribute 'get'. This previously bubbled up as a 500 Internal Server Error, confusingly attaching the extracted llm_provider to the crash response.

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Screenshots / Proof of Fix

Before:
Sending an array of strings (e.g "content": ["what is the capital of France?"]) resulted in an internal crash that returned a 500 error containing internal proxy metadata:

{
  "error": {
    "message": "'str' object has no attribute 'get'",
    "type": "server_error",
    "param": null,
    "code": null,
    "llm_provider": "openai"
  }
}

After:
The array of strings is successfully caught and normalized into the strict OpenAI multi-modal dictionary spec before downstream processing, resulting in a successful 200 response:
[{"type": "text", "text": "what is the capital of France?"}]

(Tests passing successfully locally)

Type

🐛 Bug Fix

Changes

• Updated validate_and_fix_openai_messages in litellm/utils.py to auto-normalize array-of-strings content into standard OpenAI multi-modal dictionaries.
• Added a pytest function to ensure strings within arrays are properly converted while existing dictionaries are preserved.