Cannot create custom client because typings

[sigorilla]

Describe the bug
I created my own client for "other" platform, but typings does not allow use different Client type because of union.

Interfaces for my bot:

import {Bot} from 'bottender';

interface OtherRawEvent {
    update_id: number;
    message?: TextMessage;
}

class OtherClient {
    start(): Promise<void>;
    startPolling(): Promise<void>;
    stopPolling(): void;
    isPolling(): boolean;
    receiveUpdates(updates: OtherRawEvent[]): void;
    setWebhook(url?: string): Promise<OtherClient>;
    sendMessage(chatId: string, text: string): Promise<TextMessage>;
}

class OtherEvent implements Event<OtherRawEvent> {}

class OtherContext extends Context<OtherClient, OtherEvent> {}

class OtherBot extends Bot<OtherRawEvent, OtherClient, OtherEvent, OtherContext> {}
//                                        ^^^^^^^^^^^ <- error below

Type 'OtherClient' does not satisfy the constraint 'Client'.
Type 'OtherClient' is missing the following properties from type 'TelegramClient': _token, _onRequest, _axios, axios, and 47 more. ts(2344)

Expected behavior

I think that type of Client should be like this:

export type Client =
  | ConsoleClient
  | MessengerClient
  | LineClient
  | SlackOAuthClient
  | TelegramClient
  | ViberClient
  | TwilioClient
  | unknown;

The same patch should be added to Event and Body.