What emulator are you using? I haven't gotten this error yet, I'm going to try and replicate it so that I can fix it before the deadline.
Viewing post in Tremblay Island jam comments
You were right. What happened was that I had made some engine tweaks to Butano itself, and for some reason, when I made my latest build, it seems to have undone those changes. I went back in and fixed it, and it's working now! I've uploaded the latest working build. Fingers crossed, I've only done a little bit of testing so far.