[Vuejs]-Include bootstrap in nuxt.js

The first part means you are missing some loaders that WebPack needs to bundle your styles.

Try running npm install --save vue-style-loader css-loader for that. It will install those two loaders.

These relative modules were not found: signals something else in your Index page, where you are trying to use the Footer component, but failed to import it or register it correctly. Have a look at the Vue Docs about registering your components.