### Website or app

google.com

### Repro steps

This started after last update 4.20.0
![image](https://user-images.githubusercontent.com/11052469/137713404-e6702959-7870-46a6-8566-4cfe61d25309.png)
![image](https://user-images.githubusercontent.com/11052469/137713464-c5e478d2-4e9e-4ee4-abdf-83d23c04704b.png)


### How often does this bug happen?

Every time

### DevTools package (automated)

_No response_

### DevTools version (automated)

_No response_

### Error message (automated)

_No response_

### Error call stack (automated)

_No response_

### Error component stack (automated)

_No response_

### GitHub query string (automated)

_No response_
import nullthrows from 'nullthrows';
import {installHook} from 'react-devtools-shared/src/hook';
import {
  __DEBUG__,
  SESSION_STORAGE_RELOAD_AND_PROFILE_KEY,
} from 'react-devtools-shared/src/constants';
import {CURRENT_EXTENSION_ID, EXTENSION_INSTALLATION_TYPE} from './constants';
import {sessionStorageGetItem} from 'react-devtools-shared/src/storage';
function injectCode(code) {
  const script = document.createElement('script');
  script.textContent = code;
  
  
  nullthrows(document.documentElement).appendChild(script);
  nullthrows(script.parentNode).removeChild(script);
}
let lastDetectionResult;
window.addEventListener('message', function onMessage({data, source}) {
  if (source !== window || !data) {
    return;
  }
  if (data.extensionId !== CURRENT_EXTENSION_ID) {
    if (__DEBUG__) {
      console.log(
        `[injectGlobalHook] Received message '${data.source}' from different extension instance. Skipping message.`,
        {
          currentExtension: EXTENSION_INSTALLATION_TYPE,
        },