BUG: Replacing fk control with aim_fk control errors

[TheSleepyDino]

1. Go into Regions
2. Choose the same fk control but choose "aim_fk" in the drop down
3. Rig region and you'll see an error

[TheSleepyDino]

From what I remember this breaks on any 1 joint FK controls. If you do the spine which usually has more than 1 joint, it converts to aim_fk fine.