Fatal exception fixed in DVC on macOS while wxDataViewModel::Cleared call + editing item.

src/osx/cocoa/dataview.mm

@@ -551,6 +551,11 @@ outlineView:(NSOutlineView*)outlineView
 {
     wxUnusedVar(outlineView);
 
+    // See the comment in outlineView:objectValueForTableColumn:byItem: below:
+    // this function can also be called in the same circumstances.
+    if ( implementation->GetDataViewCtrl()->IsDeleting() )
+        return nil;
+
     if ((item == currentParentItem) &&
             (index < ((NSInteger) [self getChildCount])))
         return [self getChild:index];

src/osx/dataview_osx.cpp

@@ -251,7 +251,14 @@ bool wxOSXDataViewModelNotifier::ValueChanged(wxDataViewItem const& item, unsign
 
 bool wxOSXDataViewModelNotifier::Cleared()
 {
-  return m_DataViewCtrlPtr->GetDataViewPeer()->Reload();
+  bool noFailureFlag;
+
+  // NOTE: See comments in ItemDeleted method above
+  m_DataViewCtrlPtr->SetDeleting(true);
+  noFailureFlag = m_DataViewCtrlPtr->GetDataViewPeer()->Reload();
+  m_DataViewCtrlPtr->SetDeleting(false);
+
+  return noFailureFlag;
 }
 
 void wxOSXDataViewModelNotifier::Resort()