message: Additional check for the existence of buttons
diff: @@ -356,10 +356,15 @@ class App extends React.Component<RouteComponentProps<any>, any> {
  addStartPageListeners = () => {
  // id from index.html start page
  - document.getElementById('preloaderCreateBtn').addEventListener('click', this.setCompleteCreation)
  - document.getElementById('preloaderConnectBtn').addEventListener('click', this.setCompleteCreation)
  - document.getElementById('preloaderRestoreBtn').addEventListener('click', this.setCompleteCreation)
  - document.getElementById('preloaderSkipBtn').addEventListener('click', this.setCompleteCreation)
  + const createBtn = document.getElementById('preloaderCreateBtn')
  + const connectBtn = document.getElementById('preloaderConnectBtn')
  + const restoreBtn = document.getElementById('preloaderRestoreBtn')
  + const skipBtn = document.getElementById('preloaderSkipBtn')
  +
  + if (createBtn) createBtn.addEventListener('click', this.setCompleteCreation)
  + if (connectBtn) connectBtn.addEventListener('click', this.setCompleteCreation)
  + if (restoreBtn) restoreBtn.addEventListener('click', this.setCompleteCreation)
  + if (skipBtn) skipBtn.addEventListener('click', this.setCompleteCreation)
  }
  removeStartPageListeners = () => {
  