NumericGazer has uploaded the firstaid on the download page on patreon, but since I'm not a patreon number, I don't know the way I found whether the same as it described there.
So, after I tried several times, I found that if you picked more than four stone ores to make sure that you have at least one after selling 4 to herba, the game won't crash for the error. Also for the 2nd or 3rd quest next, picking the items all up(there will be 5 on the map) and not selling all of them(just sell 4) to herba, then you could play until the end without any more crashing(I didn't try it if I don't pick them all up then whether the game will crash, but maybe this time it won't).
Maybe the code written fix the number of stone ore to one(Since you have one stone ore when you just start the game), resulting in the crashing when you just picked 3 stone ores up and sold them all, and form which the bug occurs.
Sorry for my poor English. Short story line but, have fun.