Unexpected behaviour when undoing Ctrl+G while the method created by it is entered

[radeusgd]

Nothing very serious, but the application behaves weirdly when we hit this edge case.

Enso_i0l1T1qsf9.mp4

Repro:

1. create a method using Ctrl+G.
2. enter that method via double click
3. undo creation of the method via Ctrl+Z.
4. Now weird things happen.

Actual behaviour

The method is removed, but we still see its nodes on the screen, but the nodes become disconnected. Once we exit back to main method, we can still enter this nonexistent method but the nodes do not respond to input.

Expected behaviour

We should probably be brought up one level higher (back to main method) once the method we are in gets removed. The breadcrumb (collapsed) should disappear as it is no longer valid.

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Partially the behaviour is there as when I click on the show visualization icon I get a screen 'the component you are viewing no longer exists'. I think that is the right direction but perhaps it should appear sooner? As we can still see the internals of the method even though they are no longer there. I think as soon as we press Ctrl+Z and the method we are inside of gets deleted - we should get that screen right away.