Incorrect error messages when prefix is specified but parameter is missing

[Khaleelur-Rahman]

The error messages displayed when the prefix for a parameter is specified but the parameter is missing is not specific.

Steps to reproduce :

1) Type in the command select 1 2) Type in the command add n/John Doe e/e0123456@u.nus.edu t/ 3) Error message specified is Tags names should be alphanumeric.

The error message when the tag name is empty but the prefix is given is not specific. Perhaps stating Missing tag name would have been much more clearer to the user.

A similar error unspecific error message occurs when the email id is missing.

[nus-se-bot]

Team's Response

While we recognise that a more specific error message would be beneficial for user's understanding, we found that the current implementation did not take away from the functionality of the application.

Items for the Tester to Verify

:question: Issue response

Team chose [response.NotInScope]

• [x] I disagree

Reason for disagreement: The error message Tags names should be alphanumeric is insufficient as the user did not enter any tag names for this error message to be displayed. I believe invalid and missing parameters address 2 different things and must be addressed seperately, and not under a single error message. I also observed that this error message was displayed for other paramaters too (not limited to tag names).

Quoting the website Specificity of error message: Error messages can be correct but not specific enough (e.g., it says the input is 'invalid' without giving the reason, or gives too many possible reasons without pointing out the specific reason). These cases can be considered type.FeatureFlaw.

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## :question: Issue type Team chose [`type.FunctionalityBug`] Originally [`type.FeatureFlaw`] - [x] I disagree **Reason for disagreement:** As quoted above, this is a `type.FeatureFlaw`.

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