message: Don't NPE if no third party invite
diff: @@ -1553,7 +1553,7 @@ module.exports = React.createClass({
  inviterName={inviterName}
  invitedEmail={invitedEmail}
  oobData={this.props.oobData}
  - signUrl={this.props.thirdPartyInvite.inviteSignUrl}
  + signUrl={this.props.thirdPartyInvite ? this.props.thirdPartyInvite.inviteSignUrl : null}
  room={this.state.room}
  />
  </div>
  