It doesn’t give you an error log if it’s a syntax error, but it does if it’s a semantic error. That’s because I didn’t write the code for syntax error checking myself; it’s handled by ANTLR, the parser generator library that I used. I can probably find a way to address that though.
If you can, please file a bug report describing what’s happening and what you feel should be happening instead, with the ZIP you are attempting to upload as a sprite style attached, and I’ll have a look and debug it myself.
Thanks!