Grade não carrega após lite-server | TypeScript parte 2: Mais técnicas e boas práticas

Olá! A grade parou de carregar após as modificações da parte 2 do curso de typescript. Está apresentando os seguintes erros no console :

Unchecked runtime.lastError: The message port closed before a response was received.

DevTools failed to load SourceMap: Could not load content for http://localhost:3000/css/bootstrap.css.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE

DevTools failed to load SourceMap: Could not load content for http://localhost:3000/css/bootstrap-theme.css.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE

package.json:

{
  "name": "alurabank",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "compile": "tsc",
    "watch": "tsc -w",
    "server": "lite-server --baseDir=app",
    "start": "concurrently \"npm run watch\" \"npm run server\""
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@types/jquery": "^2.0.42",
    "concurrently": "^3.4.0",
    "lite-server": "^2.3.0",
    "typescript": "^2.3.2"
  }
}

index.html:

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <title>Negociações</title>
    <link rel="stylesheet" href="css/bootstrap.css" />
    <link rel="stylesheet" href="css/bootstrap-theme.css" />
  </head>
  <body class="container">
    <h1 class="text-center">Negociações</h1>
    <div id="mensagemView"></div>
    <form class="form">
      <div class="form-group">
        <label for="data">Data</label>
        <input type="date" id="data" class="form-control" required autofocus />
      </div>
      <div class="form-group">
        <label for="quantidade">Quantidade</label>
        <input
          type="number"
          min="1"
          step="1"
          id="quantidade"
          class="form-control"
          value="1"
          required
        />
      </div>
      <div class="form-group">
        <label for="valor">Valor</label>
        <input
          id="valor"
          type="number"
          class="form-control"
          min="0.01"
          step="0.01"
          value="0.0"
          required
        />
      </div>
      <button class="btn btn-primary" type="submit">Incluir</button>
    </form>
    <br />
    <br />
    <div id="negociacoesView"></div>
    <script src="lib/jquery.min.js"></script>
    <script src="lib/system.js"></script>
    <script>
      System.defaultJSExtensions = true;
      System.import("js/app.js").catch((err) => console.error(err));
    </script>
  </body>
</html>

Resultado após rodar o comando npm start

alurabank@1.0.0 start C:\Desenv\Alura\alurabank
> concurrently "npm run watch" "npm run server"

[1] 
[1] > alurabank@1.0.0 server C:\Desenv\Alura\alurabank
[1] > lite-server --baseDir=app
[1]
[0] 
[0] > alurabank@1.0.0 watch C:\Desenv\Alura\alurabank
[0] > tsc -w
[0]
[1] Did not detect a `bs-config.json` or `bs-config.js` override file. Using lite-server defaults...
[1] ** browser-sync config **
[1] {
[1]   injectChanges: false,
[1]   files: [ './**/*.{html,htm,css,js}' ],
[1]   watchOptions: { ignored: 'node_modules' },
[1]   server: { baseDir: 'app', middleware: [ [Function], [Function] ] }
[1] }
[0] 10:47:11 - Compilation complete. Watching for file changes.
[0]
[0]
[1] [Browsersync] Access URLs:
[1]  -------------------------------------
[1]        Local: http://localhost:3000
[1]     External: http://192.168.0.17:3000
[1]  -------------------------------------
[1]           UI: http://localhost:3001
[1]  UI External: http://localhost:3001
[1]  -------------------------------------
[1] [Browsersync] Serving files from: app
[1] [Browsersync] Watching files...
[1] [Browsersync] Reloading Browsers... (buffered 7 events)
[1] 20.09.07 10:47:12 304 GET /index.html
[1] 20.09.07 10:47:12 304 GET /css/bootstrap.css
[1] 20.09.07 10:47:12 304 GET /css/bootstrap-theme.css
[1] 20.09.07 10:47:12 304 GET /lib/jquery.min.js
[1] 20.09.07 10:47:12 304 GET /lib/system.js
[1] 20.09.07 10:47:12 200 GET /js/app.js
[1] 20.09.07 10:47:12 200 GET /js/controllers/NegociacaoController.js
[1] 20.09.07 10:47:12 200 GET /js/views/NegociacoesView.js
[1] 20.09.07 10:47:12 200 GET /js/models/Negociacoes.js
[1] 20.09.07 10:47:12 200 GET /js/views/MensagemVIew.js
[1] 20.09.07 10:47:12 200 GET /js/models/Negociacao.js
[1] 20.09.07 10:47:12 200 GET /js/views/view.js
[1] 20.09.07 10:47:15 304 GET /css/bootstrap.css
[1] 20.09.07 10:47:15 304 GET /css/bootstrap-theme.css
[1] 20.09.07 10:47:15 304 GET /lib/system.js.map
[1] 20.09.07 10:47:15 404 GET /css/bootstrap.css.map
[1] 20.09.07 10:47:15 404 GET /css/bootstrap-theme.css.map

npm notice created a lockfile as package-lock.json. You should commit this file.
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: fsevents@~2.1.2 (node_modules\chokidar\node_modules\fsevents):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for fsevents@2.1.3: wanted 
{"os":"darwin","arch":"any"} (current: {"os":"win32","arch":"x64"})
npm WARN alurabank@1.0.0 No description
npm WARN alurabank@1.0.0 No repository field.

+ concurrently@3.4.0
added 14 packages from 10 contributors and audited 240 packages in 16.125s

4 packages are looking for funding
  run `npm fund` for details

found 1 low severity vulnerability
  run `npm audit fix` to fix them, or `npm audit` for details

Não sei se tem relação, mas o "npm audit fix" não resolveu essa vulnerabilidade apontada.

npm audit

=== npm audit security report ===                        


                                 Manual Review                                  
             Some vulnerabilities require your attention to resolve             



  Low             Prototype Pollution                                           

  Package         minimist                                                      

  Patched in      >=0.2.1 <1.0.0 || >=1.2.3                                     

  Dependency of   lite-server [dev]                                             

  Path            lite-server > minimist                                        

  More info       https://npmjs.com/advisories/1179                             

found 1 low severity vulnerability in 240 scanned packages
  1 vulnerability requires manual review. See the full report for details.

Devo baixar esses 2 arquivos?

bootstrap.css.map
bootstrap-theme.css.map

ou era pra ser gerado automaticamente?