throw custom error

const client = createTRPCClient<RegistrationAppRouter>({
      links: [
        loggerLink({
          enabled: (options) =>
            (config.debug === "error" && options.direction === "down" && options.result instanceof Error) ||
            config.debug === "verbose",
        }),
        httpLink({
          url: config.url,
          methodOverride: "POST",
          transformer: superjson,
        }),
      ],
    })

export const customLink: TRPCLink<AppRouter> = () => {
  return ({ next, op }) => {
    return observable((observer) => {
      const unsubscribe = next(op).subscribe({
        next(value) {
          observer.next(value)
        },
        error(error) {
          observer.error(error)
        },
        complete() {
          observer.complete()
        },
      })
      return unsubscribe
    })
  }
}