No warning when not needed

deploy.sh

@@ -37,7 +37,7 @@ git remote set-url origin "git@gitlab.epfl.ch:idevelop/howtogitlabrunner.git"
 git push -f --tags
 echo "END OF PUSH"
 
-tee_stderr="perl -pe STDERR->print(\$_);warn(\$!)"
+tee_stderr="perl -pe STDERR->print(\$_);warn(\$!)if(\$!)"
 
 echo "BEGIN UPLOAD"
 UPLOADED_FILE_URL="$(curl --request POST --header "Private-Token: ${MY_TOKEN}" --form "file=@README.pdf" "https://gitlab.epfl.ch/api/v4/projects/$PROJECT_ID/uploads" | $tee_stderr | jq -r .url)"