Inserting/Deleting a Channel when cursor doesn't exist crashes faunatone

[Savestate2A03]

To reproduce: Scenario 1: Delete channels until no more exists so the cursor disappears, then try to insert one Scenario 2: Delete channels until no more exist so the cursor disappears, undo to restore them, then try to insert/delete

Windows 10-20H2 faunatone v0.1.0