message: Catch exception if passphrase dialog cancelled
  As hopefully explained by comment
diff: @@ -40,12 +40,16 @@ export default class CompleteSecurity extends React.Component {
  onStartClick = async () => {
  const cli = MatrixClientPeg.get();
  + try {
  await accessSecretStorage(async () => {
  await cli.checkOwnCrossSigningTrust();
  });
  this.setState({
  phase: PHASE_DONE,
  });
  + } catch (e) {
  + // this will throw if the user hits cancel, so ignore
  + }
  }
  onSkipClick = () => {
  