Potential fix for code scanning alert no. 5: Information exposure through an exception

[GitTimeraider]

Potential fix for https://github.com/GitTimeraider/Directadmin-Emailforwarder/security/code-scanning/5

To fix the problem, we should avoid sending the exception details (str(e)) to the client. Instead, we should log the exception (including the stack trace) on the server for debugging purposes, and return a generic error message to the client. This change should be made in the create_forwarder function (lines 186-192). The same pattern should be checked elsewhere, but only the shown code should be changed. No new imports are needed, as traceback and print are already used for logging. The error response should simply be:

return jsonify({'error': 'Failed to create forwarder'}), 500

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