message: Fix Context#userId types
diff: @@ -26,7 +26,7 @@ export default class Context<D extends object> {
  constructor(
  nodeId: string,
  clientId: string,
  - userId: string | undefined,
  + userId: string,
  subprotocol: string,
  server: Server
  )
  @@ -67,7 +67,7 @@ export default class Context<D extends object> {
  * }
  * ```
  */
  - userId: 'server' | string | undefined
  + userId: 'server' | string
  /**
  * Unique persistence client ID.
  