Adding combined image samplers

src/Engine/Containers/Map.h

@@ -81,10 +81,18 @@ struct Map : public Tree<K, Pair<K, V>, _KeyFun<K, Pair<K, V>>, Compare, Allocat
     {
         return Super::remove(key);	
     }
+    constexpr bool exists(const key_type& key) const
+    {
+        return Super::find(key) != Super::end();
+    }
     constexpr bool exists(const key_type& key)
     {
         return Super::find(key) != Super::end();
     }
+    constexpr bool contains(const key_type& key) const
+    {
+        return exists(key);
+    }
     constexpr bool contains(const key_type& key)
     {
         return exists(key);

src/Engine/Containers/Tree.h

@@ -314,7 +314,7 @@ protected:
     constexpr iterator find(const key_type& key) const
     {
         Node* it = root;
-        while (!equal(it->data, key))
+        while (it != nullptr && !equal(it->data, key))
         {
             if (comp(key, keyFun(it->data)))
             {
@@ -325,6 +325,10 @@ protected:
                 it = it->rightChild;
             }
         }
+        if (it == nullptr)
+        {
+            return end();
+        }
         return iterator(it);
     }
     constexpr Pair<iterator, bool> insert(const NodeData& data)