[nobug] avoid possible NPE running tests with no active editor

bundles/org.eclipse.wst.xml.ui/src/org/eclipse/wst/xml/ui/internal/handlers/ToggleEditModeHandler.java

diff --git a/bundles/org.eclipse.wst.xml.ui/src/org/eclipse/wst/xml/ui/internal/handlers/ToggleEditModeHandler.java b/bundles/org.eclipse.wst.xml.ui/src/org/eclipse/wst/xml/ui/internal/handlers/ToggleEditModeHandler.java
index ead4fea..c36673f 100644
--- a/bundles/org.eclipse.wst.xml.ui/src/org/eclipse/wst/xml/ui/internal/handlers/ToggleEditModeHandler.java
+++ b/bundles/org.eclipse.wst.xml.ui/src/org/eclipse/wst/xml/ui/internal/handlers/ToggleEditModeHandler.java
@@ -100,7 +100,7 @@
 		ITextEditor textEditor = null;
 		if (editor instanceof ITextEditor)
 			textEditor = (ITextEditor) editor;
-		else {
+		else if (editor != null) {
 			Object o = editor.getAdapter(ITextEditor.class);
 			if (o != null)
 				textEditor = (ITextEditor) o;