[FIXED JENKINS-7826] it is possible that findNearest finds no match, if

the user has no read permission on any of the jobs.

changelog.html

@@ -61,6 +61,9 @@ Upcoming changes</a>
   <li class=bug>
     Failing to install a plugin from CLI should result in non-zero exit code
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-10057">issue 10057</a>)
+  <li class=bug>
+    Fixed NPE in trying to diagnose undefined job error.
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-7826">issue 7826</a>)
   <li class=bug>
     Disable auto refresh in slave markOffline screen
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-10608">issue 10608</a>)

core/src/main/java/hudson/cli/handlers/AbstractProjectOptionHandler.java

@@ -50,8 +50,13 @@ public class AbstractProjectOptionHandler extends OptionHandler<AbstractProject>
         String src = params.getParameter(0);
 
         AbstractProject s = h.getItemByFullName(src,AbstractProject.class);
-        if (s==null)
-            throw new CmdLineException(owner, "No such job '"+src+"' perhaps you meant "+ AbstractProject.findNearest(src)+"?");
+        if (s==null) {
+            AbstractProject nearest = AbstractProject.findNearest(src);
+            if (nearest!=null)
+                throw new CmdLineException(owner, "No such job '"+src+"' perhaps you meant "+ nearest +"?");
+            else
+                throw new CmdLineException(owner, "No such job '"+src+"'");
+        }
         setter.addValue(s);
         return 1;
     }

core/src/main/java/jenkins/model/Jenkins.java

@@ -2052,6 +2052,7 @@ public class Jenkins extends AbstractCIBase implements ModifiableItemGroup<TopLe
      */
     public Item getItem(String relativeName, ItemGroup context) {
         if (context==null)  context = this;
+        if (relativeName==null) return null;
 
         if (relativeName.startsWith("/"))   // absolute
             return getItemByFullName(relativeName);