Don't sort rows unless there are rows

Change-Id: Ifb9e841a70f365c49d19eb2bb12623b5cbd3c835
Reviewed-on: http://gerrit.dmdirc.com/2618
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Chris Smith <chris@dmdirc.com>

src/com/dmdirc/addons/ui_swing/components/addonbrowser/BrowserWindow.java

@@ -211,7 +211,9 @@ public class BrowserWindow extends JDialog implements ActionListener {
             /** {@inheritDoc} */
             @Override
             public void run() {
-                sorter.sort();
+                if (list.getRowCount() > 0) {
+                    sorter.sort();
+                }
             }
         });
     }