Ensure that npm is installed before running it

See gh-388

ci/scripts/stage.sh

@@ -29,7 +29,7 @@ fi
 echo "Staging ${stageVersion} (next version will be ${nextVersion})"
 run_maven versions:set -DnewVersion=${stageVersion} -DgenerateBackupPoms=false
 run_maven org.eclipse.tycho:tycho-versions-plugin:update-eclipse-metadata
-run_maven --projects io.spring.javaformat:spring-javaformat-vscode-extension -P '!formatter-dependencies' antrun:run@update-version frontend:npm@update-package-lock
+run_maven --projects io.spring.javaformat:spring-javaformat-vscode-extension -P '!formatter-dependencies' antrun:run@update-version frontend:install-node-and-npm frontend:npm@update-package-lock
 
 git config user.name "Spring Builds" > /dev/null
 git config user.email "[email protected]" > /dev/null