Firefox 60.9 Not Loading es2015 modules (Angular 8)

I have an Angular 8 application using differential loading. The production build configuration creates ES5 and ES2015 modules for differential loading. Chrome, Edge, IE11 and latest FireFox all load correctly in Windows 10.

Unfortunately, the version of FF installed in the Production Environment is 60.9 and this version has issues with the modules.

package.json


  "name": "rmt-v2",
  "version": "3.0.0",
  "scripts": {
    "ng": "ng",
    "start": "ng serve",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e",
    "build:docker": "ng b -c=docker --watch",
    "build:prod": "ng b -c=prod",
    "build:dev": "ng s -c=dev --watch"
  },
  "private": true,
  "dependencies": {
    "@ag-grid-community/all-modules": "^22.1.1",
    "@angular/animations": "~8.2.14",
    "@angular/cdk": "^8.2.3",
    "@angular/common": "~8.2.14",
    "@angular/compiler": "~8.2.14",
    "@angular/core": "~8.2.14",
    "@angular/forms": "~8.2.14",
    "@angular/platform-browser": "~8.2.14",
    "@angular/platform-browser-dynamic": "~8.2.14",
    "@angular/router": "~8.2.14",
    "@fortawesome/angular-fontawesome": "^0.5.0",
    "@fortawesome/fontawesome-svg-core": "^1.2.26",
    "@fortawesome/free-regular-svg-icons": "^5.12.0",
    "@fortawesome/free-solid-svg-icons": "^5.12.0",
    "@ng-bootstrap/ng-bootstrap": "^5.2.1",
    "@types/heatmap.js": "^2.0.36",
    "@types/leaflet": "^1.5.12",
    "@types/leaflet-draw": "^1.0.3",
    "ag-grid-angular": "^22.1.1",
    "ag-grid-community": "^22.1.1",
    "angular-bootstrap-datetimepicker": "^4.0.2",
    "angular-mocks": "^1.7.9",
    "angular-split": "^3.0.2",
    "angular-webstorage-service": "^1.0.2",
    "bootstrap": "^4.4.1",
    "classlist.js": "^1.1.20150312",
    "core-js": "^3.6.4",
    "file-saver": "^2.0.2",
    "highcharts": "^8.1.2",
    "highcharts-angular": "^2.4.0",
    "highcharts-custom-events": "^3.0.4",
    "leaflet": "^1.6.0",
    "leaflet-draw": "^1.0.4",
    "leaflet-heatmap": "^1.0.0",
    "moment-range": "^4.0.2",
    "ng2-dragula": "^2.1.1",
    "ngx-contextmenu": "^5.1.0",
    "ngx-device-detector": "^1.4.6",
    "ngx-markdown": "^9.0.0",
    "open-iconic": "^1.1.1",
    "rxjs": "~6.4.0",
    "sanitize-html": "^1.27.2",
    "tslib": "^1.13.0",
    "web-animations-js": "^2.3.2",
    "zone.js": "~0.9.1"
  },
  "devDependencies": {
    "@angular-devkit/build-angular": "~0.803.26",
    "@angular/cli": "~8.3.26",
    "@angular/compiler-cli": "~8.2.14",
    "@angular/language-service": "~8.2.14",
    "@types/core-js": "^2.5.2",
    "@types/file-saver": "^2.0.1",
    "@types/jasmine": "~3.3.8",
    "@types/jasminewd2": "~2.0.3",
    "@types/node": "~8.9.4",
    "angular-router-loader": "^0.8.5",
    "angular2-template-loader": "^0.6.2",
    "angular2-toaster": "^8.0.0",
    "autoprefixer": "^9.7.4",
    "awesome-typescript-loader": "^5.2.1",
    "babel-loader": "^8.0.6",
    "clean-webpack-plugin": "^3.0.0",
    "codelyzer": "^5.0.0",
    "cross-loader": "^0.1.0",
    "css-loader": "^3.4.2",
    "ejs-loader": "^0.3.5",
    "exports-loader": "^0.7.0",
    "file-loader": "^5.0.2",
    "html-loader": "^0.5.5",
    "html-webpack-plugin": "^3.2.0",
    "istanbul-instrumenter-loader": "^3.0.1",
    "jasmine-core": "~3.5.0",
    "jasmine-spec-reporter": "~4.2.1",
    "karma": "~4.1.0",
    "karma-chrome-launcher": "~2.2.0",
    "karma-coverage-istanbul-reporter": "~2.0.1",
    "karma-jasmine": "~2.0.1",
    "karma-jasmine-html-reporter": "^1.4.0",
    "mini-css-extract-plugin": "^0.9.0",
    "moment": "^2.24.0",
    "node-sass": "^4.14.1",
    "postcss-loader": "^3.0.0",
    "precss": "^4.0.0",
    "protractor": "~5.4.0",
    "pub": "^0.2.0",
    "pug": "^2.0.4",
    "pug-loader": "^2.4.0",
    "raw-loader": "^4.0.0",
    "source-map-loader": "^0.2.4",
    "to-string-loader": "^1.1.6",
    "ts-node": "~7.0.0",
    "tslint": "~5.15.0",
    "typescript": "~3.5.3",
    "webpack": "^4.41.5",
    "webpack-cli": "^3.3.10",
    "webpack-dev-server": "^3.11.0",
    "webpack-merge": "^4.2.2"
  }
}

Angular.json

{
  "$schema": "./node_modules/@angular/cli/lib/config/schema.json",
  "version": 1,
  "newProjectRoot": "projects",
  "projects": {
    "rmt-v2": {
      "projectType": "application",
      "schematics": {
        "@schematics/angular:component": {
          "style": "scss"
        }
      },
      "root": "",
      "sourceRoot": "src",
      "prefix": "",
      "architect": {
        "build": {
          "builder": "@angular-devkit/build-angular:browser",
          "options": {
            "showCircularDependencies": true,
            "outputPath": "dist",
            "index": "src/index.html",
            "main": "src/main.ts",
            "polyfills": "src/polyfills.ts",
            "tsConfig": "tsconfig.app.json",
            "aot": false,
            "assets": [
              "src/favicon.ico",
              "src/assets"
            ],
            "styles": [
              "./node_modules/leaflet/dist/leaflet.css",
              "./node_modules/leaflet-draw/dist/leaflet.draw.css",
              "./node_modules/bootstrap/scss/bootstrap.scss",
              "src/styles/styles.scss",
              "src/styles/_reset.css",
              "src/styles/bootstrapCustom.css"
            ],
            "scripts": [
              "./node_modules/marked/lib/marked.js",
              "./node_modules/leaflet/dist/leaflet.js",
              "./node_modules/heatmap.js/build/heatmap.min.js",
              "./node_modules/leaflet-heatmap/leaflet-heatmap.js",
              "./node_modules/leaflet-draw/dist/leaflet.draw.js",
              "./node_modules/sanitize-html/dist/sanitize-html.min.js"
            ]
          },
          "configurations": {
            "prod": {
              "fileReplacements": [
                {
                  "replace": "src/environments/environment.ts",
                  "with": "src/environments/environment.prod.ts"
                }
              ],
              "optimization": true,
              "outputHashing": "all",
              "sourceMap": false,
              "extractCss": true,
              "namedChunks": false,
              "aot": true,
              "extractLicenses": true,
              "vendorChunk": false,
              "buildOptimizer": true,
              "budgets": [
                {
                  "type": "initial",
                  "maximumWarning": "7mb",
                  "maximumError": "10mb"
                },
                {
                  "type": "anyComponentStyle",
                  "maximumWarning": "6kb",
                  "maximumError": "10kb"
                }
              ]
            },
            "docker": {
              "fileReplacements": [
                {
                  "replace": "src/environments/environment.ts",
                  "with": "src/environments/environment.docker.ts"
                }
              ],
              "optimization": false,
              "outputHashing": "all",
              "sourceMap": true,
              "extractCss": true,
              "namedChunks": false,
              "aot": false,
              "extractLicenses": true,
              "vendorChunk": true,
              "buildOptimizer": false,
              "budgets": [
                {
                  "type": "initial",
                  "maximumWarning": "2mb",
                  "maximumError": "5mb"
                },
                {
                  "type": "anyComponentStyle",
                  "maximumWarning": "6kb",
                  "maximumError": "10kb"
                }
              ]
            },
            "dev": {
              "fileReplacements": [
                {
                  "replace": "src/environments/environment.ts",
                  "with": "src/environments/environment.dev.ts"
                }
              ],
              "optimization": false,
              "outputHashing": "all",
              "sourceMap": true,
              "extractCss": true,
              "namedChunks": false,
              "aot": false,
              "extractLicenses": true,
              "vendorChunk": true,
              "buildOptimizer": false,
              "budgets": [
                {
                  "type": "initial",
                  "maximumWarning": "2mb",
                  "maximumError": "5mb"
                },
                {
                  "type": "anyComponentStyle",
                  "maximumWarning": "6kb",
                  "maximumError": "10kb"
                }
              ]
            }
          }
        },
        "serve": {
          "builder": "@angular-devkit/build-angular:dev-server",
          "options": {
            "browserTarget": "rmt-v2:build"
          },
          "configurations": {
            "production": {
              "browserTarget": "rmt-v2:build:production"
            },
            "docker": {
              "browserTarget": "rmt-v2:build:docker"
            },
            "dev": {
              "browserTarget": "rmt-v2:build:dev"
            }
          }
        },
        "extract-i18n": {
          "builder": "@angular-devkit/build-angular:extract-i18n",
          "options": {
            "browserTarget": "rmt-v2:build"
          }
        },
        "test": {
          "builder": "@angular-devkit/build-angular:karma",
          "options": {
            "main": "src/test.ts",
            "polyfills": "src/polyfills.ts",
            "tsConfig": "tsconfig.spec.json",
            "karmaConfig": "karma.conf.js",
            "assets": [
              "src/favicon.ico",
              "src/assets"
            ],
            "styles": [
              "./node_modules/bootstrap/dist/css/bootstrap.css",
              "src/styles/styles.scss",
              "src/styles/_reset.css",
              "src/styles/bootstrapCustom.css"
            ],
            "scripts": []
          }
        },
        "lint": {
          "builder": "@angular-devkit/build-angular:tslint",
          "options": {
            "tsConfig": [
              "tsconfig.app.json",
              "tsconfig.spec.json",
              "e2e/tsconfig.json"
            ],
            "exclude": [
              "**/node_modules/**"
            ]
          }
        },
        "e2e": {
          "builder": "@angular-devkit/build-angular:protractor",
          "options": {
            "protractorConfig": "e2e/protractor.conf.js",
            "devServerTarget": "rmt-v2:serve"
          },
          "configurations": {
            "production": {
              "devServerTarget": "rmt-v2:serve:production"
            }
          }
        }
      }
    }},
  "defaultProject": "rmt-v2"
}

tsconfig.json

{
  "compileOnSave": false,
  "compilerOptions": {
    "baseUrl": "./src",
    "outDir": "./dist/out-tsc",
    "sourceMap": true,
    "declaration": false,
    "downlevelIteration": true,
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    "module": "esnext",
    "moduleResolution": "node",
    "importHelpers": true,
    "target": "es2015",
    "paths": {
      "@config/*": [ "../config/*" ],
      "@app/*": ["app/*"]
    },
    "allowSyntheticDefaultImports": true,
    "typeRoots": [
      "node_modules/@types"
    ],
    "lib": [
      "es2018",
      "dom"
    ],
    "resolveJsonModule": true,
    "esModuleInterop": true,
    "skipLibCheck": true
  },
  "angularCompilerOptions": {
    "fullTemplateTypeCheck": true,
    "strictInjectionParameters": true
  }
}

The Network Tab in the Dev tools shows the following enter image description here

enter image description here

Generated Script Tags in index.html

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>My Angular 8 App</title>
  <base href="/">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="icon" type="image/x-icon" href="favicon.ico">

  <link rel="stylesheet" href="styles.94bcefb507c368697735.css">
  <link rel="stylesheet" href="main.954525c3d786f7058e13.css">
</head>
<body>
<app-root></app-root>
<script src="runtime-es2015.242f71ace90ec041b135.js" type="module"></script>
<script src="runtime-es5.242f71ace90ec041b135.js" nomodule defer></script>
<script src="polyfills-es5.4d6e5b779dfe03b63b7e.js" nomodule defer></script>
<script src="polyfills-es2015.7639006645731a3f7d9f.js" type="module"></script>
<script src="scripts.399fa4e8eb4db92676bf.js" defer></script>
<script src="main-es2015.692bc22eac2b55aeea5e.js" type="module"></script>
<script src="main-es5.692bc22eac2b55aeea5e.js" nomodule defer></script>
</body>
</html>

I can target ES5 modules only, but then IE11 breaks and I'd really prefer to maintain differential loading. I have no control over the version of FF installed in the Production Environment.

Thanks in advance!