Index: src/plugins/diagram_overlay/qgswkndiagramfactorywidget.cpp
===================================================================
--- src/plugins/diagram_overlay/qgswkndiagramfactorywidget.cpp	(revision 13891)
+++ src/plugins/diagram_overlay/qgswkndiagramfactorywidget.cpp	(working copy)
@@ -125,6 +125,14 @@
 
   //text
   QString currentText = mAttributesComboBox->currentText();
+
+  // Check for null and empty string, and then skip the rest of this stuff.
+  if( currentText.isNull() || currentText.isEmpty() )
+  {
+    delete newItem;
+    return;
+  }
+
   newItem->setText( 0, currentText );
 
   //and icon
@@ -134,10 +142,7 @@
   QColor randomColor( red, green, blue );
   newItem->setBackground( 1, QBrush( randomColor ) );
 
-  if ( !currentText.isNull() && !currentText.isEmpty() )
-  {
-    mAttributesTreeWidget->addTopLevelItem( newItem );
-  }
+  mAttributesTreeWidget->addTopLevelItem( newItem );
 }
 
 void QgsWKNDiagramFactoryWidget::removeAttribute()
Index: src/core/qgsvectorlayer.cpp
===================================================================
--- src/core/qgsvectorlayer.cpp	(revision 13891)
+++ src/core/qgsvectorlayer.cpp	(working copy)
@@ -1,6 +1,6 @@
 /***************************************************************************
+  This class implements a generic means to display vector layers. The features
                                qgsvectorlayer.cpp
-  This class implements a generic means to display vector layers. The features
   and attributes are read from the data store using a "data provider" plugin.
   QgsVectorLayer can be used with any data store for which an appropriate
   plugin is available.
Index: src/core/qgsvectoroverlay.h
===================================================================
--- src/core/qgsvectoroverlay.h	(revision 13891)
+++ src/core/qgsvectoroverlay.h	(working copy)
@@ -25,7 +25,7 @@
 class QgsRect;
 class QgsRenderContext;
 
-/**Base class for vector layer overlays (e.g. Diagrams, labels, etc.). For each object, the position of the bounding box is *stored in a QgsOberlayObject. The vector overlays are drawn on top of all layers
+/**Base class for vector layer overlays (e.g. Diagrams, labels, etc.). For each object, the position of the bounding box is *stored in a QgsOverlayObject. The vector overlays are drawn on top of all layers
 * \note This class has been added in version 1.1
 */
 class CORE_EXPORT QgsVectorOverlay