Last hotbar slot selecting glitch??

[RealSkarecrohw]

this has happened twice now-once to my sister and once to me(we're playing on my private server together)-where without fishing at all, suddenly minecraft is just. selecting the last hotbar slot? it also auto uses whatever is in that slot-so for me it was auto eating for me lol

It isn't game breaking or anything, just kind of annoying when it happens-is there anything we can do about this? or should we only have this mod installed when we plan to autofish