added error check for null.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@5321 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/model/Actionable.java

@@ -78,7 +78,10 @@ public abstract class Actionable extends AbstractModelObject {
 
     public Object getDynamic(String token, StaplerRequest req, StaplerResponse rsp) {
         for (Action a : getActions()) {
-            if(a.getUrlName().equals(token))
+            String urlName = a.getUrlName();
+            if(urlName==null)
+                throw new AssertionError("Action "+a+" returned null from the getUrlName() method");
+            if(urlName.equals(token))
                 return a;
         }
         return null;