Open perspective in e4 after detaching it results NPE

Question

I have converted my app from e3 to e4. Now after I detach any perspective in my app and than trying to open it again just getting NPE. If I restart app again getting NPE. After I delete eclipse folder than restart app its working until I detach perspective.

`

<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.4"?>
<plugin>
   <extension
         point="org.eclipse.ui.perspectives">
      <perspective
            class="com..perspective.EmptyPerspective"
            icon="icons/icn.png"
            id="com.client.perspective"
            name="%permissions.perspective.name">
      </perspective>
   </extension>
   <extension
         point="org.eclipse.ui.views">
      <e4view
            class="com.view.View"
            icon="icons/mail_sm.png"
            id="com.view.View"
            name="%permissions.view.name"
            restorable="true">
      </e4view>
   </extension>
   <extension
         point="org.eclipse.ui.perspectiveExtensions">
      <perspectiveExtension
            targetID="com.client.perspective">
         <e4view
               closeable="false"
               id="com.view.View"
               minimized="false"
               relationship="top"
               relative="org.eclipse.ui.editorss"
               visible="true">
         </view>
      </perspectiveExtension>
   </extension>
</plugin>

`