Fix merge conflict

backend/app.js

backend/public/index.html

...ublic/static/css/app.ec2d265986b1f9dcd1cffe8ec691bc1f.css

...c/static/css/app.ec2d265986b1f9dcd1cffe8ec691bc1f.css.map

backend/public/static/js/app.d7bc7e91d6675626d211.js

backend/public/static/js/app.d7bc7e91d6675626d211.js.map

...end/public/static/js/manifest.2ae2e69a05c33dfc65f8.js.map

frontend/package-lock.json

frontend/package.json

frontend/src/App.vue

frontend/src/components/BookIndexPage.vue

frontend/src/components/BookSearchPage.vue

frontend/src/components/BookShowPage.vue

frontend/src/main.js

frontend/src/router/index.js