Command+- not captured on Firefox (but does on all other browsers tested)

The shortcut command+- (where + is not a key) does not bind on Firefox. It works on the other browsers I tested - Safari, Chrome, and Brave.

Here is a reproduction:

• https://codesandbox.io/s/mousetrap-does-not-capture-command-on-firefox-de1it
• (test this): https://de1it.csb.app/

Pressing command plus - will not print zoomOut() to the DOM in Firefox, but does in other browsers.