The errors in the console after ng serve has compiled succesfully

These errors have just started to be thrown in angular 11. It was running fine in angular 8, 9, 10. This is recurrent on multiple micro services.

Polymer is being used inside of a bundle.html file and this is the first occurence.

//# sourceMappingURL=webcomponents-lite.js.map
</script>
<script>
  var Polymer = Polymer || {};
  Polymer.dom = 'shadow';
</script>
<div hidden="" by-polymer-bundler="">

Note that I was following the official migration steps from Angular10 to 11

I updated the bower.json dependencies to their latest dependencies, since webcomponents-lite.js.map is inside of the bower_components folder. No luck.
I have applied the reccomendations from this

package.json

{
  "name": "hvdc-emd-ui-connectivity",
  "version": "0.0.0",
  "scripts": {
    "preinstall": "npx [email protected]",
    "ng": "ng",
    "start": "ng serve",
    "build": "polymer-bundler --inline-scripts src/index.html>src/bundle.html | ng build",
    "prod-build": "polymer-bundler --inline-scripts src/index.html>src/bundle.html | ng build",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e"
  },
  "private": true,
  "dependencies": {
    "@angular/animations": "^11.2.14",
    "@angular/cdk": "^11.2.13",
    "@angular/common": "~11.2.14",
    "@angular/compiler": "~11.2.14",
    "@angular/core": "~11.2.14",
    "@angular/forms": "~11.2.14",
    "@angular/localize": "^11.2.14",
    "@angular/material": "^11.2.13",
    "@angular/platform-browser": "~11.2.14",
    "@angular/platform-browser-dynamic": "~11.2.14",
    "@angular/router": "~11.2.14",
    "@ng-bootstrap/ng-bootstrap": "^9.1.3",
    "@ngrx/effects": "^11.1.1",
    "@ngrx/store": "^11.1.1",
    "ag-grid-angular": "^24.1.0",
    "ag-grid-community": "^24.1.0",
    "bootstrap": "^4.6.2",
    "core-js": "^2.5.4",
    "express": "^4.18.2",
    "express-request-proxy": "^2.2.2",
    "file-saver": "^2.0.5",
    "npm-force-resolutions": "0.0.3",
    "prettier": "^2.8.8",
    "rxjs": "~6.6.7",
    "tslib": "^2.0.0",
    "zone.js": "^0.11.4"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "~0.1102.19",
    "@angular/cli": "^11.2.19",
    "@angular/compiler-cli": "~11.2.14",
    "@angular/language-service": "~11.2.14",
    "@types/jasmine": "~3.6.0",
    "@types/jasminewd2": "~2.0.3",
    "@types/node": "~8.9.4",
    "codelyzer": "^6.0.0",
    "jasmine-core": "~3.6.0",
    "jasmine-spec-reporter": "~5.0.0",
    "karma": "~6.4.3",
    "karma-chrome-launcher": "~3.1.0",
    "karma-coverage-istanbul-reporter": "~3.0.2",
    "karma-jasmine": "~4.0.0",
    "karma-jasmine-html-reporter": "^1.5.0",
    "protractor": "~7.0.0",
    "ts-node": "~7.0.0",
    "tslint": "~6.1.0",
    "typescript": "^4.1.6"
  },
  "resolutions": {
    "json-schema": "0.4.0",
    "tough-cookie": "4.1.3",
    "moment-timezone": "0.5.35",
    "lodash": "4.17.21",
    "qs": "6.10.3",
    "async": "2.6.4",
    "moment": "2.29.4"
  },
  "config": {
    "unsafe-perm": true
  }
}