TypeError: Object prototype may only be an Object or null: undefined Angular 8

Question

Whenever I try to start up my web app, I get this Type error. Can't figure out why.

I started to get it after I updated some packages. I can't figure out which one was the problem or why the code that the error points to give wrong as it is code in my dependencies for Angular 8. I am not really sure what the error is even telling me. I have tried to update all dependencies. I have looked at almost all the similar question solutions and they have not worked. I can't tell if it is a compiler error, typescript, or a dependency error.

ERROR

[error] TypeError: Object prototype may only be an Object or null: undefined
    at setPrototypeOf (<anonymous>)
    at Object.__extends (C:\Users\leahb\Desktop\NH\NH-Senior-Project\node_modules\tslib\tslib.js:65:9)
    at C:\Users\leahb\Desktop\NH\NH-Senior-Project\node_modules\@angular\compiler-cli\src\ngtsc\indexer\src\template.js:115:17

tslib.js at line 65
    (function (exporter) {
        var extendStatics = Object.setPrototypeOf ||
            ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
            function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };

        __extends = function (d, b) { 
            extendStatics(d, b); *//saying the error is coming from here*
            function __() { this.constructor = d; }
            d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
        };

PACKAGE.JSON

{
  "name": "nh",
  "version": "0.0.0",
  "scripts": {
    "ng": "ng",
    "start": "ng serve",
    "build": "ng build",
    "test": "ng test",
    "lint": "ng lint",
    "e2e": "ng e2e",
    "heroku-postbuild": "ng build --prod"
  },
  "keywords": [
    "heroku"
  ],
  "private": true,
  "dependencies": {
    "@agm/core": "^1.0.0-beta.6",
    "@angular-devkit/build-angular": "^0.13.0",
    "@angular/animations": "~8.1.2",
    "@angular/common": "~8.1.2",
    "@angular/core": "~8.1.2",
    "@angular/forms": "~8.1.2",
    "@angular/platform-browser": "~8.1.2",
    "@angular/platform-browser-dynamic": "~8.1.2",
    "@angular/router": "~8.1.2",
    "@types/googlemaps": "^3.37.0",
    "core-js": "^2.5.4",
    "font-awesome": "^4.7.0",
    "hammerjs": "^2.0.8",
    "ngx-gallery": "^5.10.0",
    "rxjs": "~6.5.2",
    "tslib": "^1.9.0",
    "zone.js": "^0.9.1"
  },
  "devDependencies": {
    "@angular/cli": "^7.3.9",
    "@angular/compiler": "^7.2.15",
    "@angular/compiler-cli": "^8.1.2",
    "@angular/language-service": "~8.1.2",
    "@types/jasmine": "~2.8.8",
    "@types/jasminewd2": "~2.0.3",
    "@types/node": "~8.9.4",
    "codelyzer": "~4.5.0",
    "enhanced-resolve": "^3.3.0",
    "jasmine-core": "~2.99.1",
    "jasmine-spec-reporter": "~4.2.1",
    "karma": "~4.0.0",
    "karma-chrome-launcher": "~2.2.0",
    "karma-coverage-istanbul-reporter": "~2.0.1",
    "karma-jasmine": "~1.1.2",
    "karma-jasmine-html-reporter": "^0.2.2",
    "protractor": "~5.4.0",
    "ts-node": "~7.0.0",
    "tslint": "~5.11.0",
    "typescript": "^3.4.5"
  },
  "engines": {
    "node": "10.16.0",
    "npm": "6.9.0"
  }
}

I expected the app to compile, build, and start up. Whenever I tried ng serve, ng test, or ng build I get this error.

Answer 1

I had the same problem with my angular@7 project after updating the CLI globally to version 8 and solve it by upgrading angular in my project to the latest version by running this command in my project directory:

ng update @angular/cli @angular/core

You can also use the allow-dirty flag to bypass the repo check:

ng update @angular/cli @angular/core --allow-dirty

Also, there are other things to watch for when upgrading that has mentioned here: https://update.angular.io/#7.0:8.0

Answer 2

I got the same error in my Angular app when running tests with ng test.

In my case, the cause of the issue was circular dependencies.

I had two classes that were part of some index.ts, but one of them imported the other one using the same index. This was causing a circular dependency because as a result of it the index.ts was imported multiple times.

Once removed the circular dependency, everything worked fine.

I was inspired by: https://stackoverflow.com/a/53123468/3497671