Fix widget to wrapper converter code

Fixes #10337

Author: m-kuhn

src/gui/editorwidgets/core/qgseditorwidgetwrapper.cpp

@@ -37,7 +37,7 @@ QgsField QgsEditorWidgetWrapper::field()
 
 QgsEditorWidgetWrapper* QgsEditorWidgetWrapper::fromWidget( QWidget* widget )
 {
-  return widget->property( "EWV2Wrapper" ).value<QgsEditorWidgetWrapper*>();
+  return qobject_cast<QgsEditorWidgetWrapper*>( widget->property( "EWV2Wrapper" ).value<QgsWidgetWrapper*>() );
 }
 
 void QgsEditorWidgetWrapper::setFeature( const QgsFeature& feature )

src/gui/editorwidgets/core/qgswidgetwrapper.cpp

@@ -31,7 +31,7 @@ QWidget* QgsWidgetWrapper::widget()
   if ( !mWidget )
   {
     mWidget = createWidget( mParent );
-    mWidget->setProperty( "EWV2Wrapper", QVariant::fromValue( this ) );
+    mWidget->setProperty( "EWV2Wrapper", QVariant::fromValue<QgsWidgetWrapper*>( this ) );
     initWidget( mWidget );
   }
 
@@ -41,12 +41,6 @@ QWidget* QgsWidgetWrapper::widget()
 void QgsWidgetWrapper::setConfig( const QgsEditorWidgetConfig& config )
 {
   mConfig = config;
-  // If an editor widget was supplied, we can initialize this now
-  if ( mWidget )
-  {
-    mWidget->setProperty( "EWV2Wrapper", QVariant::fromValue( this ) );
-    initWidget( mWidget );
-  }
 }
 
 void QgsWidgetWrapper::setContext( const QgsAttributeEditorContext& context )