`add` command: unclear error message for duplicate contacts

[kokerinks]

To recreate: add these two contacts with the following details using the add command

next, run this command: add n/testnames p/91231212 e/email@gmail.com a/testaddr g/kokerinks

Expected: This add command fails for two reasons:

• duplicate name with index 7
• duplicate github username with index 6

Hence, the error message should indicate as such.

Actual: The application does not specify where is the duplicate field, and simply shows a vague message to the user, and may cause him/her to not know why his command is not working

[nus-pe-bot]

Team's Response

Thanks for your feedback. While the main issue of not being able to add a duplicate contact is prevented, whether the GitHub username or name is duplicated is still in question. This is an amendment we will consider doing for the future.

Items for the Tester to Verify

:question: Issue response

Team chose [response.NotInScope]

• [ ] I disagree

Reason for disagreement: [replace this with your explanation]

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