It would crash when some keybindings are set to null, and the filter string is
such that only those keybindings remain visible.
The reason for the crash is that when inserting non-model items (menu section
headers in this case) you specify a column to align them to. This works on the
assumption that the number of columns is always the same. It can cope with the
case that columns are removed because they are empty for all items; but it can't
cope with the case that the getDisplayStrings function returns a lower number of
columns.
And this is what happened here: MenuViewModel.GetDisplayStrings would omit the
keybinding column when none of the entries have a keybinding. This logic is
unnecessary, the generic list rendering mechanism takes care of this, so
removing this logic fixes the crash.
We do have to make sure though that the column is really empty when there's no
keybinding, so change the logic to use FgCyan only when there's a keybinding.
0b70dfbf46