Merge branch 'fix_ui_crashes' into 'master'

Another day, another UI crash fix

See merge request OpenMW/openmw!3949

components/lua_ui/element.cpp

@@ -99,15 +99,6 @@ namespace LuaUi
                 element->create(depth + 1);
             WidgetExtension* root = element->mRoot;
             assert(root);
-            WidgetExtension* parent = root->getParent();
-            if (parent)
-            {
-                auto children = parent->children();
-                std::erase(children, root);
-                parent->setChildren(children);
-                root->widget()->detachFromWidget();
-            }
-            root->updateCoord();
             return root;
         }
 
@@ -313,9 +304,8 @@ namespace LuaUi
     {
         if (mState != Destroyed)
         {
-            if (mState != New)
+            if (mRoot != nullptr)
             {
-                assert(mRoot);
                 destroyRoot(mRoot);
                 mRoot = nullptr;
             }

components/lua_ui/widget.cpp

@@ -100,6 +100,8 @@ namespace LuaUi
 
     void WidgetExtension::attach(WidgetExtension* ext)
     {
+        if (ext->mParent != this)
+            ext->detachFromParent();
         ext->mParent = this;
         ext->mTemplateChild = false;
         ext->widget()->attachToWidget(mSlot->widget());
@@ -114,7 +116,13 @@ namespace LuaUi
 
     void WidgetExtension::detachFromParent()
     {
+        if (mParent)
+        {
+            auto children = mParent->children();
+            std::erase(children, this);
+            mParent->setChildren(children);
             mParent = nullptr;
+        }
         widget()->detachFromWidget();
     }