SC: invalid method reference produces NPE

[eric-milles]

Consider the following:

void m(java.util.function.Function<String, Integer> f) {
}
@groovy.transform.CompileStatic
void test() {
  m(Object::sleep)
}

The method reference Object::sleep is not a match for the functional interface Function<String,Integer>. The compiler currently throws NPE within StaticTypesMethodReferenceExpressionWriter for this case.

[eric-milles]