Add null check in duplicate widgets check

Description

!89 (merged) introduced a bug that can cause launcher to crash on launch after deleting a widget due to the widget info being null.

Issue(s)

!89 (merged)

Test environment

Test procedures

Technical details

Screenshots

Check list

• Self review
• Test procedure explained
• Tested on fresh install
• Tested applied as an update
• License
• Internal documentation
• User documentation