fix: NullPointerException when opening non-existing node in pagination listener

[alexanderpann]

No description provided.

[sergej-koscejev]

Does the code actually work for you with NavigationSupport? In other places this caused deadlocks and I had to change it to EditorNavigator. This would also be preferable if you had time to do it (and test it) because EditorNavigator is part of openapi and NavigationSupport isn't.

EDIT: I'm wrong here, both are part of openapi but MPS people (@artem-tikhomirov) mentioned that EditorNavigator is preferred.

[alexanderpann]

I don't get when this listener is executed. I couldn't reproduce the original issue with the freeze on my Mac before.

[sergej-koscejev]

Ok I'm going to approve this because this is an improvement, whereas the deadlock is impossible to reproduce and the samples are a pain to work with. However, I see two problems remaining in the code (not directly related to the scope of this PR): the use of NavigationSupport and the fact that the editor extensions is registered via the project but editor extensions became application-level some time in or before 2025.1.