Improve Error Message for Missing or Invalid .env Configuration

[mayank-Pareek]

Description:

When running the tool with an invalid or missing API key, base URL, or model ID in the .env file, the error message is unclear and doesn’t point to the root cause. Instead of indicating an issue with the configuration, the error suggests a decoding problem:

Error: reqwest::Error { kind: Decode, source: Error("missing field `choices`", line: 1, column: 95) }
error: process didn't exit successfully: `target\debug\mastermind.exe examples/avoid examples/link` (exit code: 1)

Screenshot:

Steps to Reproduce:

1. Set up the .env file with either:

   • A wrong or missing API_KEY
   • A wrong or missing OPENAI_API_BASE_URL
   • A wrong or missing DEFAULT_MODEL_ID

2. Run the following command:

   cargo run -- examples/avoid examples/link

   Expected Behavior:

   The error message should be more descriptive, indicating which specific configuration is missing or invalid. For example:

   Error: Invalid or missing API key for the Groq API. Please check your .env file and provide a valid key.

   Actual Behavior:

   The current error is related to missing fields (choices) and does not inform the user that the issue is due to an invalid or missing configuration.

Environment:

• Operating System: Microsoft Windows 11
• Rust version: rustc 1.81.0 (eeb90cda1 2024-09-04)
• Version of Mastermind: 0.1.0