Update object.h

Author: AzliRynz

object.h

@@ -10,15 +10,15 @@
 #define IS_STRING(value)       isObjType(value, OBJ_STRING)
 #define AS_STRING(value)       ((ObjString*)AS_OBJ(value))
 #define AS_CSTRING(value)      (((ObjString*)AS_OBJ(value))->chars)
-typedef struct Obj Obj;
+
 typedef struct ObjString ObjString;
 struct VM;
 
 typedef enum {
     OBJ_STRING,
 } ObjType;
 
-struct {
+typedef struct {
     ObjType type;
     bool is_marked;
     struct Obj* next;