Fix errors related to deleted Qt canvas

glue/core/qt/roi.py

@@ -28,7 +28,13 @@ def _draw(self):
 
     def _sync_patch(self):
         self.canvas.roi_callback = self._paint_check
-        self.canvas.update()  # QT repaint without MPL redraw
+        try:
+            self.canvas.update()  # QT repaint without MPL redraw
+        except RuntimeError:
+            # In some cases the above can raise a "wrapped C/C++ object of
+            # type ... has been deleted" error, in which case we can just
+            # ignore and carry on.
+            pass
 
     @property
     def canvas(self):

glue/viewers/common/qt/data_viewer.py

@@ -152,7 +152,13 @@ def close(self, warn=True):
             self._mdi_wrapper.close()
             self._mdi_wrapper = None
         else:
-            QtWidgets.QMainWindow.close(self)
+            try:
+                QtWidgets.QMainWindow.close(self)
+            except RuntimeError:
+                # In some cases the above can raise a "wrapped C/C++ object of
+                # type ... has been deleted" error, in which case we can just
+                # ignore and carry on.
+                pass
             ViewerBase.close(self)
 
         # We tell the toolbar to do cleanup to make sure we get rid of any