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.
if (source === 'react-devtools-content-script') {
                  switch (payload?.type) {
                    case 'fetch-file-with-cache-complete':
                      chrome.runtime.onMessage.removeListener(onPortMessage);
                      resolve(payload.value);
                      break;
                    case 'fetch-file-with-cache-error':
                      chrome.runtime.onMessage.removeListener(onPortMessage);
                      reject(payload.value);
                      break;
                  }
                }
              }
              chrome.runtime.onMessage.addListener(onPortMessage);
              chrome.devtools.inspectedWindow.eval(`
              window.postMessage({
                source: 'react-devtools-extension',
                extensionId: "${CURRENT_EXTENSION_ID}"
                payload: {
                  type: 'fetch-file-with-cache',
                  url: "${url}",
                },
              });
            `);
            };