Error Handling

Celeste provides a hierarchy of exceptions to help you handle errors gracefully. All exceptions inherit from celeste.exceptions.Error.

Exception Hierarchy

• Error: Base class for all Celeste errors.
  • ModelError
    • ModelNotFoundError: The requested model (or a default) could not be found.
  • ClientError
    • ClientNotFoundError: No client implementation exists for the provider/modality.
    • ModalityNotFoundError: No client registered for the requested modality.
  • CredentialsError
    • MissingCredentialsError: API key is missing.
    • UnsupportedProviderError: Provider is not configured in the credential system.
  • ValidationError
    • ConstraintViolationError: A parameter value violates model constraints (e.g., temperature > 2.0).
    • UnsupportedParameterError: The model doesn't support a passed parameter.
  • StreamingError
    • StreamingNotSupportedError: The model doesn't support streaming.
    • StreamNotExhaustedError: Accessed .output before stream finished.
    • StreamEmptyError: Stream produced no chunks.
  • httpx.HTTPStatusError: Underlying HTTP errors from providers (400, 401, 429, 500).

Example

import celeste
from celeste.exceptions import MissingCredentialsError, ModelNotFoundError
import httpx

try:
    response = await celeste.text.generate(
        model="gpt-4o",
        prompt="Hello"
    )

except MissingCredentialsError:
    print("Please set your OPENAI_API_KEY.")

except ModelNotFoundError:
    print("The requested model isn't available.")

except httpx.HTTPStatusError as e:
    print(f"Provider API error: {e.response.status_code} - {e.response.text}")