Fix Coverity null pointer dererence warning

nyalldawson · nyalldawson · commit 2900ae2b8e71 · 2018-04-06T14:19:09.000+10:00
(cherry-picked from a3605b5)
diff --git a/src/gui/attributetable/qgsdualview.cpp b/src/gui/attributetable/qgsdualview.cpp
@@ -571,7 +571,7 @@ void QgsDualView::viewWillShowContextMenu( QMenu *menu, const QModelIndex &atInd
       if ( !action.runable() )
         continue;
 
-      if ( !vl->isEditable() && action.isEnabledOnlyWhenEditable() )
+      if ( vl && !vl->isEditable() && action.isEnabledOnlyWhenEditable() )
         continue;
 
       QgsAttributeTableAction *a = new QgsAttributeTableAction( action.name(), this, action.id(), sourceIndex );
