tidy up npe caused by commented out image reference

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@804468 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/sigil/eclipse/ui/src/org/apache/felix/sigil/ui/eclipse/ui/editors/project/SigilProjectEditorPart.java b/sigil/eclipse/ui/src/org/apache/felix/sigil/ui/eclipse/ui/editors/project/SigilProjectEditorPart.java
index 6800ac1..0e91a61 100644
--- a/sigil/eclipse/ui/src/org/apache/felix/sigil/ui/eclipse/ui/editors/project/SigilProjectEditorPart.java
+++ b/sigil/eclipse/ui/src/org/apache/felix/sigil/ui/eclipse/ui/editors/project/SigilProjectEditorPart.java
@@ -209,7 +209,9 @@
     public void dispose()
     {
         ResourcesPlugin.getWorkspace().removeResourceChangeListener( this );
-        errorImage.dispose();
+        if ( errorImage != null ) {
+            errorImage.dispose();
+        }
         super.dispose();
     }