[BUG] Error responses are not handled correctly for google openapi/openrouter

[sambhav]

In case the API returns a 429/Rate limit exceeded, pydantic-ai throws a date-time parsing exception instead of surfacing the appropriate error message from the API around RLE(rate-limit-exceeded).

This can easily be replicated by using openrouter with one of the free gemini models.

from pydantic_ai import Agent

from pydantic_ai.models.openai import OpenAIModel

model = OpenAIModel(
    "google/gemini-2.0-flash-exp:free",
    base_url="https://openrouter.ai/api/v1",
    api_key="key",
)

agent = Agent(
    model=model,
    system_prompt='Be concise, reply with one sentence.',  
)

result = agent.run_sync('Who are you?')
print(result.data)

The above returns -

Traceback (most recent call last):
  File "/Users/sam/dev/openai/openai_demo.py", line 32, in <module>
    result = agent.run_sync('Who are you?')
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/sam/dev/openai/.venv/lib/python3.12/site-packages/pydantic_ai/agent.py", line 327, in run_sync
    return asyncio.get_event_loop().run_until_complete(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Cellar/[email protected]/3.12.6/Frameworks/Python.framework/Versions/3.12/lib/python3.12/asyncio/base_events.py", line 687, in run_until_complete
    return future.result()
           ^^^^^^^^^^^^^^^
  File "/Users/sam/dev/openai/.venv/lib/python3.12/site-packages/pydantic_ai/agent.py", line 255, in run
    model_response, request_usage = await agent_model.request(messages, model_settings)
                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/sam/dev/openai/.venv/lib/python3.12/site-packages/pydantic_ai/models/openai.py", line 152, in request
    return self._process_response(response), _map_usage(response)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/sam/dev/openai/.venv/lib/python3.12/site-packages/pydantic_ai/models/openai.py", line 207, in _process_response
    timestamp = datetime.fromtimestamp(response.created, tz=timezone.utc)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: 'NoneType' object cannot be interpreted as an integer

This happens because the error response is not correctly handled in _process_response -

ChatCompletion(id=None, choices=None, created=None, model=None, object=None, service_tier=None, system_fingerprint=None, usage=None, error={'message': 'Provider returned error', 'code': 429, 'metadata': {'raw': '{\n  "error": {\n    "code": 429,\n    "message": "Quota exceeded for aiplatform.googleapis.com/generate_content_requests_per_minute_per_project_per_base_model with base model: gemini-experimental. Please submit a quota increase request. https://cloud.google.com/vertex-ai/docs/generative-ai/quotas-genai.",\n    "status": "RESOURCE_EXHAUSTED"\n  }\n}\n', 'provider_name': 'Google'}}, user_id='user_...')

We should check for the presence of the error object and handle the other fields appropriately.

Note: I have noticed this with both google's OpenAI compat API and openrouter's gemini API.

This is what an example output response may look like

[sambhav]

This seems to happen due to inappropriate handling of type-casting by the openai client. OpenAI client always casts the response to a ChatCompletion response type, which they allow additional fields to be set on.

https://github.com/openai/openai-python/blob/89d49335a02ac231925e5a514659c93322f29526/src/openai/_models.py#L87-L100

[sydney-runkle]

PRs welcome! Thanks for outlining the issue clearly.