Add check that the editor's ESM JS files can be loaded in a browser

.github/workflows/ci.yml

@@ -310,6 +310,13 @@ jobs:
       - name: Editor Distro & ESM Bundle
         run: yarn gulp editor-esm-bundle
 
+      - name: Download Playwright
+        run: yarn playwright-install
+
+      - name: Editor ESM sources check
+        working-directory: ./test/monaco
+        run: yarn run esm-check
+
       - name: Typings validation prep
         run: |
           mkdir typings-test
@@ -322,17 +329,14 @@ jobs:
           echo "import '../out-monaco-editor-core';" > a.ts
           ../node_modules/.bin/tsc --noEmit
 
-      - name: Webpack Editor
+      - name: Package Editor with Webpack
         working-directory: ./test/monaco
-        run: yarn run bundle
+        run: yarn run bundle-webpack
 
       - name: Compile Editor Tests
         working-directory: ./test/monaco
         run: yarn run compile
 
-      - name: Download Playwright
-        run: yarn playwright-install
-
       - name: Run Editor Tests
         timeout-minutes: 5
         working-directory: ./test/monaco