Merge conflicts view destroys the editor's default marker layer

[maxbrunsfeld]

It looks like when the EditorConflictController unmounts, it destroys the TextEditor's default marker layer. This puts the editor into a bad state where subsequent attempts to decorate markers fail.

I don't remember what the problem was with adding a new layer, but in the meantime, we could just remove the call to this.layer.destroy().

/cc @smashwilson

[smashwilson]

Oh, yikes! Yeah, that should be an easy fix - thanks 😳