Fix crash with empty attribute list

Author: manisandro

src/gui/qgsattributedialog.cpp

@@ -285,9 +285,9 @@ void QgsAttributeDialog::init()
     // Set focus to first widget in list, to help entering data without moving the mouse.
     if ( mypInnerLayout->rowCount() > 0 )
     {
-      QWidget* widget = mypInnerLayout->itemAtPosition( 0, 1 )->widget();
-      if ( widget )
-        widget->setFocus( Qt::OtherFocusReason );
+      QLayoutItem* item = mypInnerLayout->itemAtPosition( 0, 1 );
+      if ( item && item->widget() )
+        item->widget()->setFocus( Qt::OtherFocusReason );
     }
 
     QSpacerItem *mypSpacer = new QSpacerItem( 0, 0, QSizePolicy::Fixed, QSizePolicy::MinimumExpanding );