In case you’re making your own nodes in C++ that rely on external .h files to be included with the code, and do so like:
{{#global}}
#include "etc.h"
{{/global}}
at the top of the code box, make sure the braces and text look exactly like that. No spaces or carriage returns between the brackets and “/global” or anything, or it won’t compile correctly. Someone might have done something like that and took a minute to figure out what was going on…