editor: Fix panic on newline below with a cursor on deleted diff hunk (#58542)

Closes FR-62

Release Notes:

- Fixed crash on newline below with a cursor on a deleted line of a
diff.
bb33fea173Smit Barmase committed on 6/4/2026, 3:39:18 PM· committed by GitHubparentc29c9ba
2 files changedLine totals unavailable