I have only now seen this, sorry for the late answer.

As I have already mentioned in another reply to the same issue, the crash is due to Stellaris Evolved overwriting a file, removing templates which are supposed to be present in vanilla. The creators behind Evolved likely missed that since the template in question isn't actually in use by the base game.

It's "tree_21_21" in "topbar_traditions_view.gui" which is used by the subservient tree from my mod. You can fix it for yourself by copy pasting the template from vanilla into the modded file.

Note that I'm naming Stellaris Evolved here because of the other comment. In your case it could be due to any mod messing with the "topbar_traditions_view.gui" file.