If you have more than one copy of React DevTools installed and enabled (e.g. the version in the Chrome store and a locally built version) they can interfere with each other.

DevTools should detect this case and warn by showing a dialog in the DevTools UI and/or by logging to the console.

Note that we _should not warn_ if a related tool like Fast Refresh is present, only another copy of DevTools.
'use strict';
const ports = {};
const IS_FIREFOX = navigator.userAgent.indexOf('Firefox') >= 0;
import {EXTENSION_INSTALL_CHECK_MESSAGE} from './constants';
chrome.runtime.onConnect.addListener(function(port) {
  let tab = null;
  let name = null;
  if (isNumeric(port.name)) {
    tab = port.name;
    name = 'devtools';
    installContentScript(+port.name);
  } else {
    tab = port.sender.tab.id;
    name = 'content-script';
  }
  if (!ports[tab]) {
    ports[tab] = {
      devtools: null,
      'content-script': null,
    };
  }
  ports[tab][name] = port;
  if (ports[tab].devtools && ports[tab]['content-script']) {
    doublePipe(ports[tab].devtools, ports[tab]['content-script']);
  }
});
function isNumeric(str: string): boolean {