ci: check code for lint errors

.gitlab-ci.yml

@@ -7,8 +7,17 @@
       - Dockerfile
 
 stages:
+  - test
   - release
 
+lint:
+  image: node:14-alpine
+  stage: test
+  before_script:
+    - npm ci
+  script:
+    - npm run lint -- --no-fix
+
 docker-push:
   # Use the official docker image.
   image: docker:latest