Can't assign unit-specific hotkey to MWHEELDOWN

[ribbanya]

To reproduce:

1. Enable Unit-Specific Hotkeys.
2. Change the dropdown from Default to any hero.
3. Attempt to assign any ability to MWHEELDOWN.

Assertion failure:

UnitSpecificKeybinds_t invalid index 49 not >= 0 and < 42

Game must exit afterward.

Possibly related to MWHEELDOWN button doesn't work for "reload" action.

 

[ribbanya]

Duplicate of Game Crashes when abilities are bound to certain inputs like Mouse Scroll Wheel or C on specific Unit Keybinds.