Thanks! I just pushed an update (build 58) that totally refactors the crafting and related inventory code, so it should be more robust now. I can't repro the issue as described in the new build.
It looks like it's mostly fixed; I'm not getting it the majority of the time. I did run into one time though. It no longer ends in an out of bounds array access, no matter how much i tried to poke it, and unlike before while it stuck in the save file it didn't stick around when I reloaded from the beginning of the stage.