- Prevent potential NPE in listener

Signed-off-by: Ansgar Radermacher <ansgar.radermacher@cea.fr>
diff --git a/core/org.polarsys.esf.core.common.ui/src/main/java/org/polarsys/esf/core/common/ui/widget/ActiveProjectControlContribution.java b/core/org.polarsys.esf.core.common.ui/src/main/java/org/polarsys/esf/core/common/ui/widget/ActiveProjectControlContribution.java
index fa19a62..92fa253 100644
--- a/core/org.polarsys.esf.core.common.ui/src/main/java/org/polarsys/esf/core/common/ui/widget/ActiveProjectControlContribution.java
+++ b/core/org.polarsys.esf.core.common.ui/src/main/java/org/polarsys/esf/core/common/ui/widget/ActiveProjectControlContribution.java
@@ -153,7 +153,7 @@
     public void partClosed(final IWorkbenchPart pPart) {
         // If the last active editor used is the one which is closed,
         // then reset the controls content to the default value
-        if (pPart.equals(mActiveEditorPart)) {
+        if (mActiveProjectComposite != null && pPart.equals(mActiveEditorPart)) {
             mActiveProjectComposite.updateActiveProjectControls(null);
         }
     }