Support selecting multiple trees and a group

[normanrz]

Selecting multiple trees (with Cmd on Mac) and a group doesn't work. There is an appropriate warning for that. However, there is also an error thrown with breaks the options in the warning modal.

How to reproduce:

• Create a hybrid annotation
• Create bunch of trees
• Create a group with at least one tree
• Select 2 trees (with Cmd)
• Try to select the group as well
• See the error below

[philippotto]

• [ ] also add to keyboard shortcuts

[daniel-wer]

I fixed the error in #4816 because I encountered it during testing. I didn't do anything else from this issue, though.