diff --git a/src/UniTask/Assets/Plugins/UniTask/Runtime/PlayerLoopHelper.cs b/src/UniTask/Assets/Plugins/UniTask/Runtime/PlayerLoopHelper.cs
index f8776a2..1aa6a61 100644
--- a/src/UniTask/Assets/Plugins/UniTask/Runtime/PlayerLoopHelper.cs
+++ b/src/UniTask/Assets/Plugins/UniTask/Runtime/PlayerLoopHelper.cs
@@ -283,14 +283,17 @@ namespace Cysharp.Threading.Tasks
 
 #endif
 
-        private static int? FindLoopSystemIndex(PlayerLoopSystem[] playerLoopList, Type systemType)
+        private static int FindLoopSystemIndex(PlayerLoopSystem[] playerLoopList, Type systemType)
         {
             for (int i = 0; i < playerLoopList.Length; i++)
             {
                 if (playerLoopList[i].type == systemType)
+                {
                     return i;
+                }
             }
-            return null;
+
+            throw new Exception("Target PlayerLoopSystem does not found. Type:" + systemType.FullName);
         }
 
         public static void Initialize(ref PlayerLoopSystem playerLoop)
@@ -301,75 +304,51 @@ namespace Cysharp.Threading.Tasks
             var copyList = playerLoop.subSystemList.ToArray();
 
             // Initialization
-            int? systemIndex = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.Initialization));
-            if (systemIndex.HasValue)
-            {
-                copyList[systemIndex.Value].subSystemList = InsertRunner(copyList[systemIndex.Value], typeof(UniTaskLoopRunners.UniTaskLoopRunnerYieldInitialization), yielders[0] = new ContinuationQueue(PlayerLoopTiming.Initialization),
+            var i = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.Initialization));
+            copyList[i].subSystemList = InsertRunner(copyList[i], typeof(UniTaskLoopRunners.UniTaskLoopRunnerYieldInitialization), yielders[0] = new ContinuationQueue(PlayerLoopTiming.Initialization),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerLastYieldInitialization), yielders[1] = new ContinuationQueue(PlayerLoopTiming.LastInitialization),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerInitialization), runners[0] = new PlayerLoopRunner(PlayerLoopTiming.Initialization),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerLastInitialization), runners[1] = new PlayerLoopRunner(PlayerLoopTiming.LastInitialization));
-            }
             // EarlyUpdate
-            systemIndex = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.EarlyUpdate));
-            if (systemIndex.HasValue)
-            {
-                copyList[systemIndex.Value].subSystemList = InsertRunner(copyList[systemIndex.Value], typeof(UniTaskLoopRunners.UniTaskLoopRunnerYieldEarlyUpdate), yielders[2] = new ContinuationQueue(PlayerLoopTiming.EarlyUpdate),
+            i = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.EarlyUpdate));
+            copyList[i].subSystemList = InsertRunner(copyList[i], typeof(UniTaskLoopRunners.UniTaskLoopRunnerYieldEarlyUpdate), yielders[2] = new ContinuationQueue(PlayerLoopTiming.EarlyUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerLastYieldEarlyUpdate), yielders[3] = new ContinuationQueue(PlayerLoopTiming.LastEarlyUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerEarlyUpdate), runners[2] = new PlayerLoopRunner(PlayerLoopTiming.EarlyUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerLastEarlyUpdate), runners[3] = new PlayerLoopRunner(PlayerLoopTiming.LastEarlyUpdate));
-            }
             // FixedUpdate
-            systemIndex = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.FixedUpdate));
-            if (systemIndex.HasValue)
-            {
-                copyList[systemIndex.Value].subSystemList = InsertRunner(copyList[systemIndex.Value], typeof(UniTaskLoopRunners.UniTaskLoopRunnerYieldFixedUpdate), yielders[4] = new ContinuationQueue(PlayerLoopTiming.FixedUpdate),
+            i = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.FixedUpdate));
+            copyList[i].subSystemList = InsertRunner(copyList[i], typeof(UniTaskLoopRunners.UniTaskLoopRunnerYieldFixedUpdate), yielders[4] = new ContinuationQueue(PlayerLoopTiming.FixedUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerLastYieldFixedUpdate), yielders[5] = new ContinuationQueue(PlayerLoopTiming.LastFixedUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerFixedUpdate), runners[4] = new PlayerLoopRunner(PlayerLoopTiming.FixedUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerLastFixedUpdate), runners[5] = new PlayerLoopRunner(PlayerLoopTiming.LastFixedUpdate));
-            }
             // PreUpdate
-            systemIndex = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.PreUpdate));
-            if (systemIndex.HasValue)
-            {
-                copyList[systemIndex.Value].subSystemList = InsertRunner(copyList[systemIndex.Value], typeof(UniTaskLoopRunners.UniTaskLoopRunnerYieldPreUpdate), yielders[6] = new ContinuationQueue(PlayerLoopTiming.PreUpdate),
+            i = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.PreUpdate));
+            copyList[i].subSystemList = InsertRunner(copyList[i], typeof(UniTaskLoopRunners.UniTaskLoopRunnerYieldPreUpdate), yielders[6] = new ContinuationQueue(PlayerLoopTiming.PreUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerLastYieldPreUpdate), yielders[7] = new ContinuationQueue(PlayerLoopTiming.LastPreUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerPreUpdate), runners[6] = new PlayerLoopRunner(PlayerLoopTiming.PreUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerLastPreUpdate), runners[7] = new PlayerLoopRunner(PlayerLoopTiming.LastPreUpdate));
-            }
             // Update
-            systemIndex = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.Update));
-            if (systemIndex.HasValue)
-            {
-                copyList[systemIndex.Value].subSystemList = InsertRunner(copyList[systemIndex.Value], typeof(UniTaskLoopRunners.UniTaskLoopRunnerYieldUpdate), yielders[8] = new ContinuationQueue(PlayerLoopTiming.Update),
+            i = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.Update));
+            copyList[i].subSystemList = InsertRunner(copyList[i], typeof(UniTaskLoopRunners.UniTaskLoopRunnerYieldUpdate), yielders[8] = new ContinuationQueue(PlayerLoopTiming.Update),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerLastYieldUpdate), yielders[9] = new ContinuationQueue(PlayerLoopTiming.LastUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerUpdate), runners[8] = new PlayerLoopRunner(PlayerLoopTiming.Update),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerLastUpdate), runners[9] = new PlayerLoopRunner(PlayerLoopTiming.LastUpdate));
-            }
             // PreLateUpdate
-            systemIndex = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.PreLateUpdate));
-            if (systemIndex.HasValue)
-            {
-                copyList[systemIndex.Value].subSystemList = InsertRunner(copyList[systemIndex.Value], typeof(UniTaskLoopRunners.UniTaskLoopRunnerYieldPreLateUpdate), yielders[10] = new ContinuationQueue(PlayerLoopTiming.PreLateUpdate),
+            i = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.PreLateUpdate));
+            copyList[i].subSystemList = InsertRunner(copyList[i], typeof(UniTaskLoopRunners.UniTaskLoopRunnerYieldPreLateUpdate), yielders[10] = new ContinuationQueue(PlayerLoopTiming.PreLateUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerLastYieldPreLateUpdate), yielders[11] = new ContinuationQueue(PlayerLoopTiming.LastPreLateUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerPreLateUpdate), runners[10] = new PlayerLoopRunner(PlayerLoopTiming.PreLateUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerLastPreLateUpdate), runners[11] = new PlayerLoopRunner(PlayerLoopTiming.LastPreLateUpdate));
-            }
             // PostLateUpdate
-            systemIndex = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.PostLateUpdate));
-            if (systemIndex.HasValue)
-            {
-                copyList[systemIndex.Value].subSystemList = InsertRunner(copyList[systemIndex.Value], typeof(UniTaskLoopRunners.UniTaskLoopRunnerYieldPostLateUpdate), yielders[12] = new ContinuationQueue(PlayerLoopTiming.PostLateUpdate),
+            i = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.PostLateUpdate));
+            copyList[i].subSystemList = InsertRunner(copyList[i], typeof(UniTaskLoopRunners.UniTaskLoopRunnerYieldPostLateUpdate), yielders[12] = new ContinuationQueue(PlayerLoopTiming.PostLateUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerLastYieldPostLateUpdate), yielders[13] = new ContinuationQueue(PlayerLoopTiming.LastPostLateUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerPostLateUpdate), runners[12] = new PlayerLoopRunner(PlayerLoopTiming.PostLateUpdate),
                                                                   typeof(UniTaskLoopRunners.UniTaskLoopRunnerLastPostLateUpdate), runners[13] = new PlayerLoopRunner(PlayerLoopTiming.LastPostLateUpdate));
-            }
 
-            systemIndex = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.Update));
-            if (systemIndex.HasValue)
-            {
-                // Insert UniTaskSynchronizationContext to Update loop
-                copyList[systemIndex.Value].subSystemList = InsertUniTaskSynchronizationContext(copyList[systemIndex.Value]);
-            }
+            // Insert UniTaskSynchronizationContext to Update loop
+            i = FindLoopSystemIndex(copyList, typeof(UnityEngine.PlayerLoop.Update));
+            copyList[i].subSystemList = InsertUniTaskSynchronizationContext(copyList[i]);
 
             playerLoop.subSystemList = copyList;
             PlayerLoop.SetPlayerLoop(playerLoop);