lib/Tools/scala

clarify error message

#!/usr/bin/env bash
#
# Author: Makarius
#
# DESCRIPTION: invoke Scala within the Isabelle environment

[ -e "$ISABELLE_HOME/Admin/build" ] && { "$ISABELLE_HOME/Admin/build" jars || exit $?; }

CLASSPATH="$(jvmpath "$CLASSPATH")"
exec "$ISABELLE_SCALA" "$@"