Invalid `add` command prints error twice

[RyanLing169]

In leaving the author section blank, two of the same errors are thrown, which do not happen for other errors

[soc-pe-bot]

[IMPORTANT!: Please do not edit or reply to this comment using the GitHub UI. You can respond to it using CATcher during the next phase of the PE]

Team's Response

Thank you for pointing out this bug. After reviewing by our dev team, we have decided to accept this bug as a severity.VeryLow since this is purely a cosmetic issue, and does not cause any inconvenience to the user, and does not hinder any functionalities of our program.

Items for the Tester to Verify

❓ Issue severity

Team chose [severity.VeryLow]
Originally [severity.Low]

• I disagree

Reason for disagreement: [replace this with your explanation]

---