chore: improve GitHub Pages deployment with safe build check

Author: eottabom

.github/workflows/deploy.yml

@@ -29,6 +29,7 @@ jobs:
           npm run build
 
       - name: Deploy to GitHub Pages
+        if: success() && (hashFiles('out/index.html') != '')
         uses: peaceiris/actions-gh-pages@v3
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}