Incompatibility with React 18: ReactDOM.render is no longer supported in React 18

[BjoernKW]

When trying to use react-singleton-hook with React 18 this error message comes up in the browser console:

react_devtools_backend.js:4026 Warning: ReactDOM.render is no longer supported in React 18. Use createRoot instead. Until you switch to the new API, your app will behave as if it's running React 17. Learn more: https://reactjs.org/link/switch-to-createroot

overrideMethod @ react_devtools_backend.js:4026
printWarning @ react-dom.development.js:86
error @ react-dom.development.js:60
render @ react-dom.development.js:29572
mount @ env.js:14
addHook @ SingletonHooksContainer.js:59
(anonymous) @ singletonHook.js:44
commitHookEffectListMount @ react-dom.development.js:23049
commitPassiveMountOnFiber @ react-dom.development.js:24816
commitPassiveMountEffects_complete @ react-dom.development.js:24781
commitPassiveMountEffects_begin @ react-dom.development.js:24768
commitPassiveMountEffects @ react-dom.development.js:24756
flushPassiveEffectsImpl @ react-dom.development.js:26990
flushPassiveEffects @ react-dom.development.js:26935
performSyncWorkOnRoot @ react-dom.development.js:26032
flushSyncCallbacks @ react-dom.development.js:12009
commitRootImpl @ react-dom.development.js:26910
commitRoot @ react-dom.development.js:26638
finishConcurrentRender @ react-dom.development.js:25937
performConcurrentWorkOnRoot @ react-dom.development.js:25765
workLoop @ scheduler.development.js:266
flushWork @ scheduler.development.js:239
performWorkUntilDeadline @ scheduler.development.js:533

This is caused by this code segment in https://github.com/Light-Keeper/react-singleton-hook/blob/main/src/utils/env.js, specifically the render() call:

// ...

import { unstable_batchedUpdates, render } from 'react-dom';

// ...
export const mount = C => {
  if (globalObject.document && globalObject.document.createElement) {
    render(<C/>, globalObject.document.createElement('div'));
  } else {
    // ...
  }
};

[vadikoom]

Hi @BjoernKW, thansk for reporintg this. Version 4.0.0 fixes the issue.

Fixed in the scope of #489