--- a/src/jdk.jpackage/share/classes/jdk/jpackage/internal/AbstractImageBundler.java	Fri May 31 08:26:31 2019 -0400
+++ b/src/jdk.jpackage/share/classes/jdk/jpackage/internal/AbstractImageBundler.java	Thu Jun 06 19:07:18 2019 -0400
@@ -128,6 +128,11 @@
                     name, outputDirectory.getAbsolutePath()));
         }
 
+        // NAME will default to CLASS, so the real problem is no MAIN_CLASS
+        if (name == null) {
+            throw new PackagerException("ERR_NoMainClass");
+        }
+
         // Create directory structure
         File rootDirectory = new File(outputDirectory, name);