message: Fixed some type errors
diff: @@ -56,7 +56,7 @@ export function findOriginOwner (doc: $rdf.NamedNode | string): string | boolean
  * @returns Returns the Web ID, after setting it
  */
  export function saveUser (
  - webId: $rdf.NamedNode | string,
  + webId: $rdf.NamedNode | string | null,
  context?: AuthenticationContext
  ): $rdf.NamedNode | null {
  // @@ TODO Remove the need for having context as output argument
  @@ -1036,7 +1036,7 @@ export function checkUser<T> (
  */
  export function loginStatusBox (
  dom: HTMLDocument,
  - listener: ((uri: string) => void) | null = null,
  + listener: ((uri: string | null) => void) | null = null,
  options: {
  buttonStyle?: string
  } = {}
  