Problem: WError error on macosx because NAN is a float

Solution: Add explicit cast from NAN to double

cJSON.c

@@ -106,7 +106,7 @@ CJSON_PUBLIC(double) cJSON_GetNumberValue(const cJSON * const item)
 {
     if (!cJSON_IsNumber(item)) 
     {
-        return NAN;
+        return (double) NAN;
     }
 
     return item->valuedouble;