I keep getting this error message for StudentswithUI.java as implemented in the manual

Exception in thread "main" java.lang.ExceptionInInitializerError

              at myMasonTest.StudentsWithUI.main(StudentsWithUI.java:17)

Caused by: java.lang.NullPointerException: Cannot invoke "java.net.URL.toExternalForm()" because "location" is null

              at java.desktop/javax.swing.ImageIcon.<init>(ImageIcon.java:234)

              at sim.display.Console.iconFor(Console.java:173)

              at sim.display.Console.<clinit>(Console.java:176)

              ... 1 more

I’ve searched all over for a solution to this and haven’t found one in the listserv, it is obviously a configuration problem but I do not know what is incorrectly configured

Jon West