message: Fix NPE in RoomRecoveryReminder
  Also fix a bug introduced in
  where I failed to set the button caption in one case.
  Fixes
diff: @@ -62,7 +62,7 @@ export default class RoomRecoveryReminder extends React.PureComponent {
  let unverifiedDevice;
  for (const sig of backupSigStatus.sigs) {
  - if (!sig.device.isVerified()) {
  + if (sig.device && !sig.device.isVerified()) {
  unverifiedDevice = sig.device;
  break;
  }
  @@ -133,12 +133,11 @@ export default class RoomRecoveryReminder extends React.PureComponent {
  const AccessibleButton = sdk.getComponent("views.elements.AccessibleButton");
  let body;
  - let primaryCaption;
  + let primaryCaption = _t("Set up");
  if (this.state.error) {
  body = <div className="error">
  {_t("Unable to load key backup status")}
  </div>;
  - primaryCaption = _t("Set up");
  } else if (this.state.unverifiedDevice) {
  // A key backup exists for this account, but the creating device is not
  // verified.
  