diff --git a/Source/Editor/CustomEditors/CustomEditorsUtil.cpp b/Source/Editor/CustomEditors/CustomEditorsUtil.cpp
index 0542fa260..a02ad1c4a 100644
--- a/Source/Editor/CustomEditors/CustomEditorsUtil.cpp
+++ b/Source/Editor/CustomEditors/CustomEditorsUtil.cpp
@@ -57,8 +57,9 @@ void OnBinaryModuleLoaded(BinaryModule* module);
 
 MonoReflectionType* CustomEditorsUtil::GetCustomEditor(MonoReflectionType* refType)
 {
+    if (!refType)
+        return nullptr;
     MonoType* type = mono_reflection_type_get_type(refType);
-
     Entry result;
     if (Cache.TryGet(type, result))
     {
@@ -68,7 +69,6 @@ MonoReflectionType* CustomEditorsUtil::GetCustomEditor(MonoReflectionType* refTy
             return MUtils::GetType(editor->GetNative());
         }
     }
-
     return nullptr;
 }
 
diff --git a/Source/Editor/CustomEditors/CustomEditorsUtil.cs b/Source/Editor/CustomEditors/CustomEditorsUtil.cs
index debd43cba..6c20b4ed4 100644
--- a/Source/Editor/CustomEditors/CustomEditorsUtil.cs
+++ b/Source/Editor/CustomEditors/CustomEditorsUtil.cs
@@ -107,6 +107,8 @@ namespace FlaxEditor.CustomEditors
 
         internal static CustomEditor CreateEditor(ScriptType targetType, bool canUseRefPicker = true)
         {
+            if (targetType == ScriptType.Null)
+                return new GenericEditor();
             if (targetType.IsArray)
             {
                 return new ArrayEditor();
diff --git a/Source/Editor/Scripting/ScriptType.cs b/Source/Editor/Scripting/ScriptType.cs
index 8ddb2a514..c56d2b8d3 100644
--- a/Source/Editor/Scripting/ScriptType.cs
+++ b/Source/Editor/Scripting/ScriptType.cs
@@ -1121,7 +1121,7 @@ namespace FlaxEditor.Scripting
                 return new ScriptType(_managed.MakeArrayType());
             if (_custom != null)
                 return new ScriptType(new ScriptTypeArray(this));
-            return Null;
+            throw new ArgumentNullException();
         }
 
         /// <summary>
@@ -1130,6 +1130,8 @@ namespace FlaxEditor.Scripting
         /// <returns>A type object representing a dictionary of the key and value types.</returns>
         public static ScriptType MakeDictionaryType(ScriptType keyType, ScriptType valueType)
         {
+            if (keyType == Null || valueType == Null)
+                throw new ArgumentNullException();
             return new ScriptType(typeof(Dictionary<,>).MakeGenericType(TypeUtils.GetType(keyType), TypeUtils.GetType(valueType)));
         }
 
diff --git a/Source/Editor/Scripting/TypeUtils.cs b/Source/Editor/Scripting/TypeUtils.cs
index 9b4b0be5e..cc8f082f6 100644
--- a/Source/Editor/Scripting/TypeUtils.cs
+++ b/Source/Editor/Scripting/TypeUtils.cs
@@ -327,16 +327,10 @@ namespace FlaxEditor.Scripting
                 return ScriptType.Null;
 
             // C#/C++ types
-            var assemblies = AppDomain.CurrentDomain.GetAssemblies();
-            for (int i = 0; i < assemblies.Length; i++)
             {
-                var assembly = assemblies[i];
-                if (assembly != null)
-                {
-                    var type = assembly.GetType(typeName);
-                    if (type != null)
-                        return new ScriptType(type);
-                }
+                var type = Type.GetType(typeName);
+                if (type != null)
+                    return new ScriptType(type);
             }
 
             // Custom types
@@ -348,6 +342,7 @@ namespace FlaxEditor.Scripting
             }
             if (typeName.EndsWith("[]"))
             {
+                // Array of custom type
                 if (typeName[0] == '.')
                     typeName = typeName.Substring(1);
                 typeName = typeName.Substring(0, typeName.Length - 2);
@@ -359,6 +354,7 @@ namespace FlaxEditor.Scripting
                 }
             }
 
+            Editor.LogWarning($"Failed to find type '{typeName}'.");
             return ScriptType.Null;
         }
 
diff --git a/Source/Editor/Windows/Assets/VisualScriptWindow.cs b/Source/Editor/Windows/Assets/VisualScriptWindow.cs
index 2cb8fc0e8..378fe8e32 100644
--- a/Source/Editor/Windows/Assets/VisualScriptWindow.cs
+++ b/Source/Editor/Windows/Assets/VisualScriptWindow.cs
@@ -201,7 +201,12 @@ namespace FlaxEditor.Windows.Assets
                     }
                     else
                     {
-                        if (isArray)
+                        if (param.Type == ScriptType.Null)
+                        {
+                            b = cmType.ContextMenu.AddButton(window.Surface.GetTypeName(param.Type) + "...", () => OnChangeType(item => window.SetParamType(index, (ScriptType)item.Tag)));
+                            return;
+                        }
+                        else if (isArray)
                         {
                             singleValueType = param.Type.GetElementType();
                             arrayType = param.Type;