Login modal not popping up after clicking "Save and sync"

[liumcse]

Describe the bug
Login modal not popping up after clicking "Save and sync" on Scheduler Page when the user is not logged in.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://developer.ntuvibe.com/scheduler, log out if you are currently logged in
2. Click Create to create a timetable
3. Click Save and sync
4. Login modal should pop up to ask you to log in. But it didn't.

Expected behavior
Login modal should pop up to ask you to log in.

Screenshots
If applicable, add screenshots to help explain your problem.

Browser (check all that apply):

• Chrome
• Firefox
• Edge
• Safari 11
• Safari 10
• IE 11

Additional context
When you fix the bug, please check out from develop branch, NOT master.