fix: 4th attempt for: now able to delete schedule even if active

[Wizardbacon13]

Fixes #401
First 2 images was after changes, third image is before changes

Also, SCSS seems to have an update where they no longer support @import and now use @use, which is why I changed certain .scss files or else "pnpm build" wouldn't have worked due to errors

Also also, I changed Instructor.ts because it outputs an error due to it not seeing any data and thinking there should be an error, making me fail one of the github checks, so I modified it so it doesn't output this error when there're no schedules.

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This change is 

[sentry-io]

🔍 Existing Issues For Review

Your pull request is modifying functions with the following pre-existing issues:

📄 File: src/pages/background/lib/deleteSchedule.ts

Function	Unhandled Issue
deleteSchedule	Error: Cannot delete active schedule deleteSchedu... Event Count: 3 Affected Users: 2
deleteSchedule	Error: Schedule h4HkkyYCWZ45 does not exist delet... Event Count: 1 Affected Users: 20

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[IsaDavRod]

LGTM (Sam should address Instructor.ts through his PR)

[doprz]

This file shouldn't be updated in this PR. The Chromatic bug is resolved with #425

[doprz]

Will review with more detail soon.