feat(examples): add robust error handling script

[Abdul565656]

This PR adds a new example script, examples/error_handling.py, to demonstrate how to gracefully handle the common API errors documented in the README (AuthenticationError, NotFoundError, BadRequestError, etc.).

This is a common requirement for developers building robust applications, and having a dedicated, runnable example will be a valuable resource. The script is designed to run successfully even if the OPENAI_API_KEY is not set, making it easy for new users to test.

Key Features of the Example:

• Shows how to use try...except for specific openai error types.
• Demonstrates how to access useful debugging information from the exception object, such as status_code, request_id, and the error message from the response body.
• Intentionally triggers errors to provide a working demonstration.
• Gracefully skips tests that require a valid API key if one is not provided.

This addresses a gap in the current examples and should help new users get up to speed on best practices for production-ready code.