diff --git a/src/Builtin/BaseProcesses.cs b/src/Builtin/BaseProcesses.cs
index d172d1b..8f226f1 100644
--- a/src/Builtin/BaseProcesses.cs
+++ b/src/Builtin/BaseProcesses.cs
@@ -45,19 +45,19 @@ namespace DCFApixels.DragonECS
 #if DEBUG && !DISABLE_DEBUG
                 for (int i = 0; i < targets.Length && targets.Length <= _markers.Length; i++)
                 {
+                    _markers[i].Begin();
                     try
                     {
-                        _markers[i].Begin();
                         targets[i].PreInit(pipeline);
-                        _markers[i].End();
                     }
                     catch (Exception e)
                     {
 #if DISABLE_CATH_EXCEPTIONS
-                        throw;
+                        throw e;
 #endif
                         EcsDebug.PrintError(e);
                     }
+                    _markers[i].End();
                 }
 #else
                 foreach (var item in targets)
@@ -66,7 +66,7 @@ namespace DCFApixels.DragonECS
                     catch (Exception e)
                     {
 #if DISABLE_CATH_EXCEPTIONS
-                        throw;
+                        throw e;
 #endif
                         EcsDebug.PrintError(e);
                     }
@@ -93,19 +93,19 @@ namespace DCFApixels.DragonECS
 #if DEBUG && !DISABLE_DEBUG
                 for (int i = 0; i < targets.Length && targets.Length <= _markers.Length; i++)
                 {
+                    _markers[i].Begin();
                     try
                     {
-                        _markers[i].Begin();
                         targets[i].Init(pipeline);
-                        _markers[i].End();
                     }
                     catch (Exception e)
                     {
 #if DISABLE_CATH_EXCEPTIONS
-                        throw;
+                        throw e;
 #endif
                         EcsDebug.PrintError(e);
                     }
+                    _markers[i].End();
                 }
 #else
                 foreach (var item in targets)
@@ -114,7 +114,7 @@ namespace DCFApixels.DragonECS
                     catch (Exception e)
                     {
 #if DISABLE_CATH_EXCEPTIONS
-                        throw;
+                        throw e;
 #endif
                         EcsDebug.PrintError(e);
                     }
@@ -141,19 +141,19 @@ namespace DCFApixels.DragonECS
 #if DEBUG && !DISABLE_DEBUG
                 for (int i = 0; i < targets.Length && targets.Length <= _markers.Length; i++)
                 {
+                    _markers[i].Begin();
                     try
                     {
-                        _markers[i].Begin();
                         targets[i].Run(pipeline);
-                        _markers[i].End();
                     }
                     catch (Exception e)
                     {
 #if DISABLE_CATH_EXCEPTIONS
-                        throw;
+                        throw e;
 #endif
                         EcsDebug.PrintError(e);
                     }
+                    _markers[i].End();
                 }
 #else
                 foreach (var item in targets)
@@ -162,7 +162,7 @@ namespace DCFApixels.DragonECS
                     catch (Exception e)
                     {
 #if DISABLE_CATH_EXCEPTIONS
-                        throw;
+                        throw e;
 #endif
                         EcsDebug.PrintError(e);
                     }
@@ -189,19 +189,19 @@ namespace DCFApixels.DragonECS
 #if DEBUG && !DISABLE_DEBUG
                 for (int i = 0; i < targets.Length && targets.Length <= _markers.Length; i++)
                 {
+                    _markers[i].Begin();
                     try
                     {
-                        _markers[i].Begin();
                         targets[i].Destroy(pipeline);
-                        _markers[i].End();
                     }
                     catch (Exception e)
                     {
 #if DISABLE_CATH_EXCEPTIONS
-                        throw;
+                        throw e;
 #endif
                         EcsDebug.PrintError(e);
                     }
+                    _markers[i].End();
                 }
 #else
                 foreach (var item in targets)
@@ -210,7 +210,7 @@ namespace DCFApixels.DragonECS
                     catch (Exception e)
                     {
 #if DISABLE_CATH_EXCEPTIONS
-                        throw;
+                        throw e;
 #endif
                         EcsDebug.PrintError(e);
                     }
diff --git a/src/Debug/EcsDebugUtility.cs b/src/Debug/EcsDebugUtility.cs
index 83a8541..0b2a083 100644
--- a/src/Debug/EcsDebugUtility.cs
+++ b/src/Debug/EcsDebugUtility.cs
@@ -2,7 +2,6 @@
 using System.Collections.Generic;
 using System.Reflection;
 using System.Runtime.CompilerServices;
-using System.Text.RegularExpressions;
 
 namespace DCFApixels.DragonECS
 {
diff --git a/src/EcsWorld.pools.cs b/src/EcsWorld.pools.cs
index c047cd2..b9d02f0 100644
--- a/src/EcsWorld.pools.cs
+++ b/src/EcsWorld.pools.cs
@@ -70,7 +70,8 @@ namespace DCFApixels.DragonECS
         }
         private TPool CreatePool<TPool>() where TPool : IEcsPoolImplementation, new()
         {
-            if (_poolIds.Contains(EcsTypeCode.Get<TPool>()))
+            int poolTypeCode = EcsTypeCode.Get<TPool>();
+            if (_poolIds.Contains(poolTypeCode))
                 throw new EcsFrameworkException("The pool has already been created.");
 
             Type componentType = typeof(TPool).GetInterfaces().First(o => o.IsGenericType && o.GetGenericTypeDefinition() == typeof(IEcsPoolImplementation<>)).GetGenericArguments()[0];
@@ -78,12 +79,12 @@ namespace DCFApixels.DragonECS
 
             if (_componentIds.TryGetValue(componentTypeCode, out int componentID))
             {
-                _poolIds[componentTypeCode] = componentID;
+                _poolIds[poolTypeCode] = componentID;
             }
             else
             {
                 componentID = _poolsCount++;
-                _poolIds[componentTypeCode] = componentID;
+                _poolIds[poolTypeCode] = componentID;
                 _componentIds[componentTypeCode] = componentID;
             }
 
diff --git a/src/Pools/EcsTagPool.cs b/src/Pools/EcsTagPool.cs
index 496af44..2256c93 100644
--- a/src/Pools/EcsTagPool.cs
+++ b/src/Pools/EcsTagPool.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Reflection;
 using System.Runtime.CompilerServices;
 
 namespace DCFApixels.DragonECS
@@ -18,6 +19,18 @@ namespace DCFApixels.DragonECS
 
         private T _fakeComponent;
 
+
+        private static bool _isInvalidType;
+        static EcsTagPool()
+        {
+            _isInvalidType = typeof(T).GetFields(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic).Length > 0;
+        }
+        public EcsTagPool()
+        {
+            if (_isInvalidType)
+                throw new EcsFrameworkException($"{typeof(T).Name} type must not contain any data.");
+        }
+
         #region Properites
         public int Count => _count;
         int IEcsPool.Capacity => -1;
diff --git a/src/entlong.cs b/src/entlong.cs
index dc1d730..ab56ba7 100644
--- a/src/entlong.cs
+++ b/src/entlong.cs
@@ -137,22 +137,6 @@ namespace DCFApixels.DragonECS
         }
         #endregion
 
-        #region Equals
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public bool Equals(entlong other) => full == other.full;
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public bool Equals(long other) => full == other;
-        #endregion
-
-        #region Object
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public override int GetHashCode() => unchecked((int)full) ^ (int)(full >> 32);
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public override string ToString() => $"entity(id:{id} g:{gen} w:{world} {(IsNull ? "null" : IsAlive ? "alive" : "not alive")})";
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public override bool Equals(object obj) => obj is entlong other && full == other.full;
-        #endregion
-
         #region operators
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static bool operator ==(entlong a, entlong b) => a.full == b.full;
@@ -169,7 +153,18 @@ namespace DCFApixels.DragonECS
         public static explicit operator int(entlong a) => a.ID;
         #endregion
 
-        #region DebuggerProxy
+        #region Other
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public override int GetHashCode() => unchecked((int)full) ^ (int)(full >> 32);
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public override string ToString() => $"entity(id:{id} g:{gen} w:{world} {(IsNull ? "null" : IsAlive ? "alive" : "not alive")})";
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public override bool Equals(object obj) => obj is entlong other && full == other.full;
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public bool Equals(entlong other) => full == other.full;
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public bool Equals(long other) => full == other;
+
         internal class DebuggerProxy
         {
             private List<object> _componentsList;