An EndException is raised when you call Quit. It causes the application to quit gracefully. Usually you do not see the EndException unless you use a "catch-all" exception statement.
||NOTE: Whenever you inadvertently catch an EndException, you MUST re-raise it. Failing to do so will confuse the runtime environment and lead to unpredictable problems. See Exception statement for more information about its proper use.
RuntimeException class; Function, Raise statements; Nil datatype; Exception, Try statements.