Combine update loops in game client

Scenes/GameScene/GameClient.gd

@@ -201,45 +201,31 @@ func _execute_action(action: Dictionary):
 		Action.Type.CHANGE_BUFFGROUP: ActionChangeBuffgroup.execute(action, player)
 
 
-# NOTE: need to check that nodes are inside tree during
-# iteration because they may get removed during iteration.
-# For example, timer_list is obtained once before iteration
-# starts. Then timer A triggers an explosion which kills a
-# creep which carries timer B. Timer B is now outside tree
-# but still inside timer_list!
 func _update_state():
 	_game_time.update(_tick_delta)
 
+#	NOTE: use separate groups so that update() calls are
+#	ordered by type. This makes gameplay logic more
+#	consistent.
 	var timer_list: Array = get_tree().get_nodes_in_group("manual_timers")
-	for timer in timer_list:
-		if !_should_update(timer):
-			continue
-
-		timer.update(_tick_delta)
-
 	var creep_list: Array[Creep] = Utils.get_creep_list()
-	for creep in creep_list:
-		if !_should_update(creep):
-			continue
-
-		creep.update(_tick_delta)
-
 	var projectile_list: Array = get_tree().get_nodes_in_group("projectiles")
-	for projectile in projectile_list:
-		if !_should_update(projectile):
-			continue
-
-		projectile.update(_tick_delta)
-
 	var tower_list: Array[Tower] = Utils.get_tower_list()
-	for tower in tower_list:
-		if !_should_update(tower):
+	var node_list: Array = []
+	node_list.append_array(timer_list)
+	node_list.append_array(creep_list)
+	node_list.append_array(projectile_list)
+	node_list.append_array(tower_list)
+
+# 	NOTE: need to check is_inside_tree() because nodes may
+# 	get removed during iteration. For example, timer_list is
+# 	obtained once before iteration starts. Then timer A
+# 	triggers an explosion which kills a creep which carries
+# 	timer B. Timer B is now outside tree but still inside
+# 	timer_list!
+	for node in node_list:
+		var should_update: bool = node.is_inside_tree() && !node.is_queued_for_deletion()
+		if !should_update:
 			continue
 
-		tower.update(_tick_delta)
-
-
-func _should_update(node: Node) -> bool:
-	var should_update: bool = node.is_inside_tree() && !node.is_queued_for_deletion()
-
-	return should_update
+		node.update(_tick_delta)