Dev server run (yarn run serve) yields error?

[Udiknedormin]

When run from the main directory, after yarn run install completed:

> yarn run serve
yarn run v1.19.2
$ vue-cli-service serve --host matey.io
 INFO  Starting development server...
 WARN  A new version of sass-loader is available. Please upgrade for best experience.
10% building 2/2 modules 0 activeevents.js:183
      throw er; // Unhandled 'error' event
      ^

Error: getaddrinfo ENOTFOUND matey.io
    at errnoException (dns.js:50:10)
    at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:92:26)
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

Having updated sass-loader to 8.0.0 and consecutive dependencies until everything works, yarn run serve still yields:

> yarn run serve
yarn run v1.19.2
$ vue-cli-service serve --host matey.io
 INFO  Starting development server...
10% building 2/2 modules 0 activeevents.js:183
      throw er; // Unhandled 'error' event
      ^

Error: getaddrinfo ENOTFOUND matey.io
    at errnoException (dns.js:50:10)
    at GetAddrInfoReqWrap.onlookup [as oncomplete] (dns.js:92:26)
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

What may be surprising is that yarn run build seems to actually complete successfully, yielding just style warnings (line breaks-related ones, it seems):

> yarn run build
yarn run v1.19.2
$ vue-cli-service build

⠸  Building for production...

 WARNING  Compiled with 4 warnings                                                                                                                             23:02:16

Module Warning (from ./node_modules/eslint-loader/index.js):
warning: Replace `·@update="onUpdatedFunds"·:expense="currentExpense"·:edit="editMode"` with `⏎········@update="onUpdatedFunds"⏎········:expense="currentExpense"⏎········:edit="editMode"⏎······` (prettier/prettier) at src/views/CurrentExpensesView.vue:45:17:
  43 |     </b-modal>
  44 |     <b-modal :active.sync="addModal">
> 45 |       <modal-add @update="onUpdatedFunds" :expense="currentExpense" :edit="editMode"></modal-add>
     |                 ^
  46 |     </b-modal>
  47 |   </section>
  48 | </template>


1 warning found.
1 warning potentially fixable with the `--fix` option.

Module Warning (from ./node_modules/eslint-loader/index.js):
warning: Replace `·data:·idList` with `⏎········data:·idList⏎·····` (prettier/prettier) at src/views/ShopListView.vue:99:65:
   97 |         .items.filter(listItem => listItem.checked === true)
   98 |         .map(item => item.id);
>  99 |       await this.$http.delete("shoplist/" + listId + "/items", { data: idList });
      |                                                                 ^
  100 |       await this.getLists();
  101 |       this.currentExpense = {
  102 |         name: "",


1 warning found.
1 warning potentially fixable with the `--fix` option.

You may use special comments to disable some warnings.
Use // eslint-disable-next-line to ignore the next line.
Use /* eslint-disable */ to ignore all warnings in a file.
 warning  

asset size limit: The following asset(s) exceed the recommended size limit (244 KiB).
This can impact web performance.
Assets: 
  css/app.161a825c.css (483 KiB)
  css/chunk-vendors.2aeb5162.css (323 KiB)
  js/chunk-vendors.d6d6eaa9.js (786 KiB)

 warning  

entrypoint size limit: The following entrypoint(s) combined asset size exceeds the recommended limit (244 KiB). This can impact web performance.
Entrypoints:
  app (1.58 MiB)
      css/chunk-vendors.2aeb5162.css
      js/chunk-vendors.d6d6eaa9.js
      css/app.161a825c.css
      js/app.d96a79c1.js


  File                                    Size              Gzipped

  dist/js/chunk-vendors.d6d6eaa9.js       786.47 KiB        203.24 KiB
  dist/js/app.d96a79c1.js                 21.93 KiB         7.22 KiB
  dist/js/chunk-4b5f6baf.2c023317.js      17.52 KiB         5.29 KiB
  dist/js/chunk-69faea36.c2887d79.js      12.82 KiB         3.48 KiB
  dist/js/chunk-9f66dc00.4bc872a4.js      8.33 KiB          2.64 KiB
  dist/js/chunk-0ef90cdb.b7a0f9f3.js      5.66 KiB          2.17 KiB
  dist/css/app.161a825c.css               483.35 KiB        54.48 KiB
  dist/css/chunk-vendors.2aeb5162.css     323.22 KiB        39.38 KiB
  dist/css/chunk-4b5f6baf.c1e69f53.css    0.90 KiB          0.39 KiB
  dist/css/chunk-69faea36.dd4847e9.css    0.38 KiB          0.21 KiB
  dist/css/chunk-9f66dc00.4b809478.css    0.14 KiB          0.13 KiB
  dist/css/chunk-0ef90cdb.f680bd9d.css    0.10 KiB          0.10 KiB

  Images and other types of assets omitted.

 DONE  Build complete. The dist directory is ready to be deployed.

My system is Ubuntu 18.04.1 64-bit. The env.development.local file is just unchanged .env.local.sample.