Issue when class property initialization happen inside, a method called inside of constructor

[iamchathu]

TypeScript Version: Version 3.5.3

Search Terms:

Class property initialization, error TS2564: Property has no initializer and is not definitely assigned in the constructor.

Code

export class NetworkConnection extends EventEmitter {

  private intervalId: NodeJS.Timeout;

  public constructor(timeout = 60000) {
    super();
    this.start(timeout);
  }

  public start = (timeout: number) => {
    this.intervalId = setInterval(this.broadcast, timeout);  
  };

  public stop = () => {
    clearInterval(this.intervalId);
  };

...
}

Expected behavior:

Run without compile error.

Actual behavior:

error TS2564: Property 'intervalId' has no initializer and is not definitely assigned in the constructor.

Playground Link:

Related Issues: #24446 #21132

[MartinJohns]

Duplicate of #21132, not just a related issue. And #30462 is an open proposal regarding this.