UnboundLocalError in OpenAI-compatible validate_credentials

[Blackoutta]

Summary

Credential validation can raise UnboundLocalError when a network exception occurs before response is assigned.

Problem

In dify_plugin/interfaces/model/openai_compatible/llm.py, the validate_credentials method wraps the HTTP call in a broad except Exception and constructs an error message that references response.text. If requests.post(...) raises before response is assigned (connection error, timeout, DNS failure), the handler itself throws UnboundLocalError: cannot access local variable 'response', masking the real failure.

Expected Behavior

Credential validation should surface the underlying request error without throwing a secondary UnboundLocalError.

Actual Behavior

Validation fails with UnboundLocalError in the error handler, hiding the original root cause.

Steps to Reproduce

1. Configure a model provider credential with an invalid or unreachable endpoint_url, or just with an turned-off Wifi.
2. A credential validation will be triggered on save.
3. Observe UnboundLocalError instead of the original request exception.

Impact

• Masks the real failure cause in validation.
• Prevents correct error reporting to users.

Proposed Fix

Initialize response = None before the request and only read response.text when response is assigned. Keep the error message focused on the root exception.