Followup 166a52b: don't disable tools that don't have commands

Using null and undefined to mean different things is ugly,
but I can't think of a better way to get us out of this mess
quickly right now.

Bug: T75965
Change-Id: I5344821ad36c8689c6c0d70e50ac0b3fcf599711
Merge "Followup 166a52b: don't disable tools that don't have commands"