properly return exit code of shell scripts to prevent travis build to succeed with failed npm commands

Author: justadudewhohacks

ci/cover/script/run-cover.sh

@@ -9,4 +9,5 @@ lcov -c -d ../build/Debug -o $(pwd)/coverage/capture.info
 lcov -e coverage/capture.info '*/cc/*' -o $(pwd)/coverage/capturedcc.info
 lcov -t opencv4nodejs -a coverage/capturedcc.info -o $(pwd)/coverage/opencv4nodejs.info
 genhtml --output-directory coverage $(pwd)/coverage/opencv4nodejs.info
-mv coverage/opencv4nodejs.info coverage-report
+mv coverage/opencv4nodejs.info coverage-report
+exit $?

ci/test/script/run-test.sh

@@ -6,4 +6,5 @@ echo running tests
 cd ./test
 npm install --unsafe-perm
 npm run test-docker
-npm run test-externalMemTracking
+npm run test-externalMemTracking
+exit $?