[TypeScript] Externals: Why getResolve returns such union?

[krutoo]

Hi, im noticed that return type of getResolve (field in first param of externals function) has next signature:

type ExternalItemFunctionData = {
  // [...]
  getResolve?: (options?: ResolveOptions) => ((context: string, request: string, callback: ResolveCallback) => void) | ((context: string, request: string) => Promise<string>);
}

This is the reason why it is not possible to use result function without third argument (callback)

It is by design or something temporary solution?