Fix crashes when opening scale/rotation popovers during selection box operations

[bdach]

The rotation and scale handlers sort of assumed that they would not be interfered with by another operation, but they actually can be - e.g. try rotating a selection via the rotate handle and then pressing Ctrl-R. It'll die on an exception. This PR changes it so that doing the same doesn't open the rotate popover.

You could argue that the other thing that could be done is to commit the previous operation, but I kinda don't wanna go there because that will be messy to handle.

[ppy-sentryintegration[bot]]

Sentry issue: OSU-1CDT

[ppy-sentryintegration[bot]]

Sentry issue: OSU-1CEA