[fix]: Improve Error Handling in StockService

[0PrashantYadav0]

Description

• Detailed Description:
  The current error handling in StockService catches generic exceptions and returns a basic JSON error message. This can make it harder to diagnose the underlying issue.
• How to Solve:
  1. Catch Specific Exceptions:
     Instead of catching a general Exception, catch more specific exceptions (e.g., RestClientException).
  2. Log Detailed Errors:
     Log the error details (including stack traces) using a logging framework for better diagnostics.
  3. Return Consistent Error Messages:
     Provide structured JSON error responses that include a message and possibly an error code:

     catch (RestClientException e) {
         logger.error("API request failed for URL {}: {}", url, e.getMessage());
         return "{\"error\": \"Failed to fetch stock price. Please try again later.\"}";
     }

  4. Test Error Scenarios:
     Simulate failures (e.g., by providing an invalid API key) and verify that errors are handled and logged as expected.