fix: add type checking before deploying changes to master

.github/workflows/pr.yml

@@ -1,4 +1,4 @@
-name: Check pull request
+name: Pull request
 
 on:
   pull_request:

.github/workflows/prod.yml

@@ -5,10 +5,30 @@ on:
     branches: [ master ]
 
 jobs:
+
+  tsc:
+
+    name: Check types
+
+    runs-on: ubuntu-latest
+
+    steps:
+
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Typescript
+        run: npm run tsc
+
   deploy:
 
     runs-on: ubuntu-latest
 
+    needs: tsc
+
     steps:
     - uses: actions/checkout@v2