edit works on contacts that dont exist

[Derekljh]

Description of the bug:
I decided to try and edit number 5 to test and see if an index error would occur. However, it turned out to show me a message success, with tags of the professors from SOC faculty? Not too sure where these contacts popped up from when the addressbook.json only shows me 2 contacts.

Steps to recreate the bug:

1. Before this, I only have 2 contacts in the list in the addressbook.json file
2. type edit -5 joe
3. Message success: Edited Person: joe; Phone: 66017690; Email: null; Address: COM3-02-47; Tags: [Assistant_Professor][SOC_faculty]
4. open up addressbook.json file to check

Here are some screenshots:

Before:

After:

This is the end of this bug report.