SKNonnullScreenGlobalForKey

#ifdef CONFIG_DEBUG
static inline id _SKNonnullScreenGlobalForKey(id self, SEL _cmd, SKScreenGlobals * aGlobals, NSString * key) {
    NSParameterAssert(self != nil);
    NSParameterAssert(_cmd != NULL);
    NSParameterAssert(aGlobals != nil);
    NSParameterAssert(key != nil);

    id object = [aGlobals objectForKey:key];
    NSAssert(object != nil, @"%@ expects the screen global for key %@ to be set.", NSStringFromClass([self class]), key);

    return object;
}
#define SKNonnullScreenGlobalForKey(key) _SKNonnullScreenGlobalForKey(self, _cmd, aGlobals, key)
#else
#define SKNonnullScreenGlobalForKey(key) [aGlobals objectForKey:key]
#endif