if you have an event/closure like:

mods.gregtech.materialEvent {
  method(, arg1, arg2)
}

the error incorrectly points to { as the issue, instead of the errant comma in method()

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
  Unexpected input: '{'
  mods.gregtech.materialEvent {
                              ^

Groovy issue. Not really anything i can do about it

Took a deeper look and can confirm that fixing this issue might be impossible without fundamentaly changing the parser