map draft-4 javascript exceptions to CWL permanentFailures

Author: mr-c

draft-4/concepts.md

@@ -351,6 +351,9 @@ Implementations may apply other limits, such as process isolation, timeouts,
 and operating system containers/jails to minimize the security risks associated
 with running untrusted code embedded in a CWL document.
 
+Exceptions thrown from an exception must result in a `permanentFailure` of the
+process.
+
 ## Success and failure
 
 A completed process must result in one of `success`, `temporaryFailure` or