Refs #30419. Unset factory when destroying InstrumentWidgetMaskTab.

qt/widgets/instrumentview/inc/MantidQtWidgets/InstrumentView/InstrumentWidgetMaskTab.h

@@ -73,6 +73,7 @@ public:
   };
 
   explicit InstrumentWidgetMaskTab(InstrumentWidget *instrWidget);
+  ~InstrumentWidgetMaskTab();
   void initSurface() override;
   void setMode(Mode mode);
   void selectTool(Activity tool);

qt/widgets/instrumentview/src/InstrumentWidgetMaskTab.cpp

@@ -370,6 +370,10 @@ InstrumentWidgetMaskTab::InstrumentWidgetMaskTab(InstrumentWidget *instrWidget)
           SLOT(enableApplyButtons()));
 }
 
+InstrumentWidgetMaskTab::~InstrumentWidgetMaskTab() {
+  m_browser->unsetFactoryForManager(m_doubleManager);
+}
+
 /**
  * Initialize the tab when new projection surface is created.
  */