Running `freethousand` causes firefox to be closed

[pcapel]

Expected Behavior:

Given a hung rails server
When I run freethousand
Then it kills the process running my rails server.

Observed Behavior:

Given a hung rails server
When I run freethousand
Then it kills the process running my rails server
And it kills the process running all my open firefox windows

Operating System: 5.4.27-1 Manjaro
Firefox: 74 for Manjaro