Updating node.yml workflow from template

Signed-off-by: Nextcloud bot <bot@nextcloud.com>

.github/workflows/node.yml

@@ -13,6 +13,9 @@ on:
       - master
       - stable*
 
+permissions:
+  contents: read
+
 jobs:
   build:
     runs-on: ubuntu-latest
@@ -41,3 +44,13 @@ jobs:
         run: |
           npm ci
           npm run build --if-present
+
+      - name: Check webpack build changes
+        run: |
+          bash -c "[[ ! \"`git status --porcelain `\" ]] || exit 1"
+
+      - name: Show changes on failure
+        if: failure()
+        run: |
+          git status
+          git --no-pager diff