Cannot assign WebSocket or SockJS to IStompSocket on TypeScript

[tearfur]

Got this error:

TS2322: Type '() => WebSocket' is not assignable to type '() => IStompSocket'.
  Call signature return types 'WebSocket' and 'IStompSocket' are incompatible.
    The types of 'onmessage' are incompatible between these types.
      Type '((this: WebSocket, ev: MessageEvent<any>) => any) | null' is not assignable to type '((ev: IStompSocketMessageEvent) => any) | null | undefined'.
        Type '(this: WebSocket, ev: MessageEvent<any>) => any' is not assignable to type '(ev: IStompSocketMessageEvent) => any'.
          Types of parameters 'ev' and 'ev' are incompatible.
            Type 'IStompSocketMessageEvent' is missing the following properties from type 'MessageEvent<any>': lastEventId, origin, ports, source, and 23 more.

It's really easy to reproduce with code like this:

const stompClient = new Client({ /* ... */ });

stompClient.webSocketFactory = function () {
  return new WebSocket(url);
};

This is what I have to do as a workaround:

const stompClient = new Client({ /* ... */ });

stompClient.webSocketFactory = function () {
  return new WebSocket(url) as IStompSocket;
};

stompjs 7.0.0
TypeScript 5.7.3