viewer: destroy text edit explicitly

Fix assert failure

app/widget/viewer/viewerdisplay.cpp

@@ -81,6 +81,13 @@ ViewerDisplayWidget::ViewerDisplayWidget(QWidget *parent) :
   inner_widget()->setAcceptDrops(true);
 }
 
+ViewerDisplayWidget::~ViewerDisplayWidget()
+{
+  delete text_edit_;
+
+  MANAGEDDISPLAYWIDGET_DEFAULT_DESTRUCTOR_INNER;
+}
+
 void ViewerDisplayWidget::SetMatrixTranslate(const QMatrix4x4 &mat)
 {
   translate_matrix_ = mat;

app/widget/viewer/viewerdisplay.h

@@ -68,7 +68,7 @@ public:
    */
   ViewerDisplayWidget(QWidget* parent = nullptr);
 
-  MANAGEDDISPLAYWIDGET_DEFAULT_DESTRUCTOR(ViewerDisplayWidget)
+  virtual ~ViewerDisplayWidget() override;
 
   const ViewerSafeMarginInfo& GetSafeMargin() const;
   void SetSafeMargins(const ViewerSafeMarginInfo& safe_margin);