Thank you very much for reporting these! It looks like the error you ran into is for deleting specifically the first preset. Looks like some wackiness with GML and arrays, fixed now. For the constant error messages, though, I can create something to ignore them, I think.
P.S. This is taking longer than I thought, (I think I forgot to finish bugfixing presets before releasing. Doh.) so I'm going to just upload when done. Shouldn't be that much longer.
EDIT: It's up now - can you test it and tell me if it worked?