Fix potential NPE

diff --git a/eu.etaxonomy.taxeditor.navigation/src/main/java/eu/etaxonomy/taxeditor/navigation/key/polytomous/PolytomousKeyViewPart.java b/eu.etaxonomy.taxeditor.navigation/src/main/java/eu/etaxonomy/taxeditor/navigation/key/polytomous/PolytomousKeyViewPart.java
index 90119ecc4329dcc47682657ee4f72caac647f74f..9e5cacf4a679509ba0acf41292679691d40e4fd9 100644 (file)
--- a/eu.etaxonomy.taxeditor.navigation/src/main/java/eu/etaxonomy/taxeditor/navigation/key/polytomous/PolytomousKeyViewPart.java
+++ b/eu.etaxonomy.taxeditor.navigation/src/main/java/eu/etaxonomy/taxeditor/navigation/key/polytomous/PolytomousKeyViewPart.java
@@ -39,6 +39,7 @@ import eu.etaxonomy.cdm.api.application.CdmApplicationState;
 import eu.etaxonomy.cdm.api.application.CdmChangeEvent;
 import eu.etaxonomy.cdm.api.application.CdmChangeEvent.Action;
 import eu.etaxonomy.cdm.api.application.ICdmChangeListener;
+import eu.etaxonomy.cdm.api.application.ICdmDataChangeService;
 import eu.etaxonomy.cdm.api.conversation.ConversationHolder;
 import eu.etaxonomy.cdm.api.conversation.IConversationEnabled;
 import eu.etaxonomy.cdm.api.service.IPolytomousKeyService;
@@ -259,7 +260,10 @@ public class PolytomousKeyViewPart extends ViewPart implements
            if(cdmEntitySession != null) {
                cdmEntitySession.dispose();
            }
-           CdmApplicationState.getCurrentDataChangeService().unregister(this);
+           ICdmDataChangeService currentDataChangeService = CdmApplicationState.getCurrentDataChangeService();
+           if(currentDataChangeService!=null){
+               currentDataChangeService.unregister(this);
+           }
                super.dispose();
        }