diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 136f4d82..e871b332 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -46,6 +46,9 @@ jobs:
       - name: Build Node.js code
         run: yarn run build:prod
 
+      - name: Run eslint
+        run: yarn run lint:ci
+
       - name: Run smoke test
         run: VERBOSE=1 DEBUG=1 MOCHA_WEBDRIVER_HEADLESS=1 yarn run test:smoke
 
diff --git a/app/server/lib/HostedStorageManager.ts b/app/server/lib/HostedStorageManager.ts
index fe18cb1d..30f64298 100644
--- a/app/server/lib/HostedStorageManager.ts
+++ b/app/server/lib/HostedStorageManager.ts
@@ -923,7 +923,7 @@ export async function backupSqliteDatabase(src: string, dest: string,
   } finally {
     if (testProgress) { testProgress({action: 'close', phase: 'before'}); }
     try {
-      if (db) { await fromCallback(cb => db.close(cb)); }
+      if (db) { await fromCallback(cb => db!.close(cb)); }
     } catch (err) {
       _log.debug(null, `problem stopping copy of ${src} (${label}): ${err}`);
     }
diff --git a/package.json b/package.json
index a1912df9..f46141f9 100644
--- a/package.json
+++ b/package.json
@@ -22,8 +22,9 @@
     "test:python": "sandbox_venv3/bin/python sandbox/grist/runtests.py ${GREP_TESTS:+discover -p \"test*${GREP_TESTS}*.py\"}",
     "cli": "NODE_PATH=_build:_build/stubs:_build/ext node _build/app/server/companion.js",
     "lint": "eslint --cache --cache-strategy content .",
-    "lint:fix": "eslint  --cache --cache-strategy content --fix .",
-    "generate:translation": "NODE_PATH=_build:_build/stubs:_build/ext node buildtools/generate_translation_keys.js"
+    "lint:fix": "eslint  --cache --cache-strategy=content --fix .",
+    "lint:ci": "eslint --max-warnings=0 .",
+    "generate:translation": "NODE_PATH=_build:_build/stubs:_build/ext node buildtools/generate_translation_keys.js",
   },
   "keywords": [
     "grist",