Deleted command pod bug

If you make some connectable part be in a mirror mode around a tank, then disconnect whole craft with mirrored part from the main pod and after that connect the pod to the mirror part, now if you click on the properties of the pod it will say "set primary", which means you can delete it. If you delete it, then the whole craft will break, and upon making undo it will say "an error occured" and if you try to launch the craft, everything but the new default rocket that was placed during the error will vanish and never return because you cant undo. I lost an unsaved replica to this, and i lost 4 hours of progress. Hope you fix that bug soon.