exit with status 1 on maven error

gitlab/run_mvn.sh

@@ -2,5 +2,5 @@
 
 mvn -s "${CI_PROJECT_DIR}/settings.xml" -B -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=warn "$@"
 if [[ "$?" -ne 0 ]] ; then
-  echo 'Maven command failed!'; exit
+  echo 'Maven command failed!'; exit 1
 fi