message: Check IS v2 account tokens for validity
  Fixes
diff: @@ -56,16 +56,10 @@ export default class IdentityAuthClient {
  return token;
  }
  - _checkToken(token) {
  - // TODO: Test current API token via `/account` endpoint
  + async _checkToken(token) {
  + await MatrixClientPeg.get().getIdentityAccount(token);
  - // At the moment, Sydent doesn't implement `/account`, so we can't use
  - // that yet. We could try a lookup for a null address perhaps...?
  - // Sydent doesn't currently expire tokens, but we should still be testing
  - // them in any case.
  - // See also https://github.com/vector-im/riot-web/issues/10452.
  -
  - // In any case, we should ensure the token in `localStorage` is cleared
  + // We should ensure the token in `localStorage` is cleared
  // appropriately. We already clear storage on sign out, but we'll need
  // additional clearing when changing ISes in settings as part of future
  // privacy work.
  @@ -86,7 +80,9 @@ export default class IdentityAuthClient {
  // See https://github.com/vector-im/riot-web/issues/10443
  console.warn("IS doesn't support v2 auth");
  this.authEnabled = false;
  + return;
  }
  + console.error(err);
  }
  }
  }
  