Unable to add book

[nus-pe-script]

Describe the bug Unable to use the add command properly. A valid 13-digit ISBN number was used. However, it is unable to add the book into the system.

To Reproduce Steps to reproduce the behavior:

1. Type in add n/How to add book? i/978-3-16-148410-1 p/19.99 c/15.00 q/50 t/Mitch t/Albom
2. Error come out despite being a valid ISBN number.

Expected behavior Expect to successfully add in the book.

Screenshots

Additional context Add any other context about the problem here.

OS and Java Version

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_{[original: dummy#27]}