shopify-scripts: Crash: mrb_any_to_s can't handle NilClass, Symbol and Fixnum

When using boxingword.h haven't tested other boxing methods yet, mrbanytos is unable to handle NilClass, Symbol and Fixnum. This can be achieved by just deleting :tos from the class and let mrbanytos crash. I tried to come up with a fix but I'm not 100% sure where this should be fixed. The boxing...