It's funny, because to combat that you either need to keep items in your stash to easily swap them, or you need to R-click --> move item to stash. However, the latter involves quickly pressing a button right next to "sell item," so I can only imagine that trying to stash swap without items already in the stash will lead to even more mistakes! Maybe they should make stash swapping more streamlined?
Either way, it's probably something that will happen extremely rarely, and might never impact a "meaningful" game. Was still insane to watch, and it turned the tide of the game completely once Tinker was neutered.