fix(BulletBase): 修复子弹分裂和折射时的空引用问题

确保在子弹分裂和折射时检查返回的子弹对象是否有效，避免空引用异常

scripts/Contents/Bullets/Parrier.gd

@@ -39,3 +39,7 @@ func hitBullet(bullet: BulletBase): # 当前子弹与其他子弹相撞
 				):
 					if b is ParryBallBullet:
 						b.atk = atk * bullet.baseDamage
+func refract(_newBullet: BulletBase, _entity: EntityBase, _index: int, _total: int, _lastBullet: float):
+	return null
+func split(_newBullet: BulletBase, _index: int, _total: int, _lastBullet: float):
+	return null

scripts/Contents/Bullets/ParryBall.gd

@@ -13,6 +13,7 @@ func destroy(_beacuseMap: bool):
 func ai():
 	PresetBulletAI.selfRotate(self , 5)
 	hitbox.disabled = !launcher.sprinting # 玩家在冲刺时气的碰撞箱才生效
+	hitbox.global_position = launcher.position
 func succeedToHit(_dmg: float, entity: EntityBase): # 当撞到敌人时
 	for bullet in BulletBase.generate(
 		ComponentManager.getBullet("QKSword"),

scripts/Statemachine/BulletBase.gd

@@ -37,6 +37,7 @@ var initialSpeed: float = 0
 var initialDamage: float = 0
 var speedScale: float = 1
 var isFirstFrame: bool = true
+var cycleStateAngle: float = 0
 
 func _ready():
 	initialSpeed = speed
@@ -182,7 +183,9 @@ func trySplit():
 			cloned.launcher = launcher
 			if is_instance_valid(parent):
 				cloned.parent = parent
-			get_parent().add_child.call_deferred(split(cloned, i, total, last))
+			var splited = split(cloned, i, total, last)
+			if !is_instance_valid(splited): continue
+			get_parent().add_child.call_deferred(splited)
 func tryRefract():
 	if is_instance_valid(launcher) and canDuplicateSelf:
 		var value = launcher.fields.get(FieldStore.Entity.BULLET_REFRACTION)
@@ -204,7 +207,9 @@ func tryRefract():
 				cloned.launcher = launcher
 				if is_instance_valid(parent):
 					cloned.parent = parent
-				get_parent().add_child.call_deferred(refract(cloned, entity, i, total, last))
+				var refracted = refract(cloned, entity, i, total, last)
+				if !is_instance_valid(refracted): continue
+				get_parent().add_child.call_deferred(refracted)
 
 # 抽象方法
 func firstFrame():

scripts/Statemachine/CycleTimer.gd

@@ -12,13 +12,15 @@ func start():
 	running = true
 func lifetime():
 	return Time.get_ticks_msec() - startTime
-func periodPercent(count: int):
-	return lifetime() / period * deg_to_rad(360) - deg_to_rad(360.0 * count / len(bullets))
+func getStateAngle(index: int):
+	return lifetime() / period * deg_to_rad(360) - deg_to_rad(360.0 * index / len(bullets))
 func apply():
 	bullets = bullets.filter(is_instance_valid)
 	for index in len(bullets):
 		var bullet = bullets[index]
-		var offset = Vector2.from_angle(periodPercent(index))
+		var newStateAngle = lerp_angle(bullet.cycleStateAngle, getStateAngle(index), 0.1)
+		var offset = Vector2.from_angle(newStateAngle)
+		bullet.cycleStateAngle = newStateAngle
 		offset.y *= 0.25
 		bullet.position = bullet.launcher.position + offset * distance
 		bullet.scale = Vector2.ONE * (1 + offset.y)