I was playing the Eastern Tundra and went through the sub-quest with the frost leaves. The person/thing in the first room was an exclamation point (!), which I assume is a placeholder sprite, so it seemed funky from the start. Killing the plants went fine and there were no problems until I collected all 5 roots and finished the sub-quest. I clicked on one of them to drag and convert it, but just as I clicked, this error occurred:
First error I've gotten so far in this lovely beta!