🛠️ fix: Completion Edge Cases & Improve Error Handling UX

[danny-avila]

Summary

Closes #3966

• Refactored the BaseClient class to handle different types of completion responses, including string arrays for parameter-based endpoints.
• Modified the OpenAIClient to properly handle cases where the chat completion response has no choices or undefined messages.
• Improved error handling in the OpenAIClient to return intermediate replies as strings when available
• Added a new error type INVALID_REQUEST to the ErrorTypes enum in the data provider package.
• Implemented specific error handling for invalid requests in the abortMiddleware, setting a custom error message for better clarity.
• Updated the client-side error handling to include the new INVALID_REQUEST error type, providing a more informative message to users.
• Added a new localization string for the invalid request error in English.

Testing

Attempt to reproduce #3966 after these changes, observe a more informative error message instead of an empty response

Checklist

• My code adheres to this project's style guidelines
• I have performed a self-review of my own code
• I have commented in any complex areas of my code
• I have made pertinent documentation changes
• My changes do not introduce new warnings
• I have added necessary error handling and logging
• Local unit tests pass with my changes