Fix crash when keybindings are disabled that normally show in the status bar (#5655)

If a keybinding that we want to display in the options bar was set to
`<disabled>` by the user, in pre-0.62 versions we would still display
the command, but with no keybinding. This was arguably not very useful
before, but now it actually crashes because we would now try to display
the first key of the slice of configured keys (crash introduced in
3d18ee8f91c7). Fix the crash by not showing those commands at all.