Clipboard not "supported" in Firefox

[martinlyra]

Describe the bug
When using Firefox, using Ctrl+C and Ctrl+V when selecting an area of stuff on the map doesn't yield anything or give no feedback.

Every time it is attempted, this appears in the console.

What browser are you using?
Firefox 77.0.1 (64-bit)

Additional context
None.

[martinlyra]

Also see #7 (comment).