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

Question

Below if I import Entity I get the posts's subject error (TypeError: Object prototype may only be an Object or null: undefined), but if I replace the import with the actual Entity declaration the code runs fine.

Stackblitz demo here.

This is Customer.ts in the form that produces the error when I run the code with ts-node:

index.ts

export { Customer } from "./Customer";
export { Entity } from "./Entity";

Customer.ts

import { Entity } from "./index";

export class Customer extends Entity {
  sku: string;
  constructor(po: any) {
    super();
    this.sku = po.sku;
  }
}

Entity.ts

export abstract class Entity {
  id?: string;
}    

Run.ts (The test code)

import {Customer} from "./";

let c = new Customer({
  name: "Bob"
});
console.log(c);

If I replace the Entity import with the declaration like this:

export abstract class Entity {
  id?: string;
}    

export class Customer extends Entity {
  sku: string;
  constructor(po: any) {
    super();
    this.sku = po.sku;
  }
}

Then Run.ts logs this:

Customer { sku: undefined }

In other words it runs fine and produces no errors. Thoughts?

Answer 1

This is not directly an answer to the example above, but I got the same error message when I had Vue and Parcel, and this kind of code:

class Proxy {}

class MyProxy extends Proxy {}

After some lengthy debugging, it turned out that there seems to be some class name conflict with the name "Proxy", maybe from Parcel. After I renamed the super class as "AbstractProxy" or anything else than "Proxy", it started to work.