Hi,
A somewhat annoying bug that happens when accidentaly using the wrong shortcut:
I assigned Shift+Alt+mouse wheel to scroll between foreground tiles, for some reason I thought i assigned it to something else, so when I used the shortcut on a project that didn’t have any tilemap layer, aseprite crashed immediately (apparently it tried to access an inexistent tilemap). But then I tried adding a tilemap layer to the project and the sortcut worked fine.
I will deactivate the shortcut for now, but anyway, I think the bug should be fixed 
Thanks!