Non-working code for library setup check

--- a/package.json
+++ b/package.json
@@ -16,5 +16,8 @@
  "devDependencies": {
    "tslint": "^6.1.3",
    "typescript": "^4.2.4"
  },
  "dependencies": {
    "sweetalert2": "^10.16.7"
  }
 }
--- a/src/index.html
+++ b/src/index.html
@@ -9,6 +9,10 @@
 <body>
    <h1>Basic setup for Typescript usage with normal HTML files</h1>
    <p>Open the console to see a console message written via typescript</p>

    <p>You can also check whether external libraries are loaded (you need to be running this from a server)</p>
    <button id="library-check-button">Check SweetAlert2 is loaded</button>
    <script src="./scripts/script.js"></script>
    <script type="module" src="./scripts/library-check.js"></script>
 </body>
 </html>
--- a/src/scripts/library-check.ts
+++ b/src/scripts/library-check.ts
@@ -0,0 +1,7 @@
 import Swal from 'sweetalert2';

 document.addEventListener('DOMContentLoaded', function () {
    document.getElementById('library-check-button')?.addEventListener('click', function () {
        Swal.fire('Library loaded successfully');
    })
 })
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -5,7 +5,7 @@
    /* Basic Options */
    // "incremental": true,                         /* Enable incremental compilation */
    "target": "es5",                                /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019', 'ES2020', or 'ESNEXT'. */
    "module": "commonjs",                           /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
    "module": "ESNext",                             /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', 'es2020', or 'ESNext'. */
    "lib": ["dom", "dom.iterable", "esnext"],       /* Specify library files to be included in the compilation. */
    // "allowJs": true,                             /* Allow javascript files to be compiled. */
    // "checkJs": true,                             /* Report errors in .js files. */
@@ -43,7 +43,7 @@
    // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */

    /* Module Resolution Options */
    // "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
    "moduleResolution": "node",                     /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
    // "baseUrl": "./",                             /* Base directory to resolve non-absolute module names. */
    // "paths": {},                                 /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
    // "rootDirs": [],                              /* List of root folders whose combined content represents the structure of the project at runtime. */