[Bug] app booting multiple times following a live reload

[roomman]

🐞 Describe the Bug

Error: Assertion Failed: You cannot use the same root element (body) multiple times in an Ember.Application is appearing in my console, after a live reload.

🔬 Minimal Reproduction

• Run ember s to launch app.
• Open inspector (Safari and/or Chrome).
• Refresh page and check console for errors.
• Make random change to template and save.
• Wait for live reload and check console for errors.

😕 Actual Behavior

After a manual page refresh there are no errors. After a live reload Error: Assertion Failed: You cannot use the same root element (body) multiple times in an Ember.Application is shown.

🤔 Expected Behavior

No errors in console.

🌍 Environment

• Ember: 4.4.0
• Node.js/npm: 16.13.2/8.4.1
• OS: Mac OSX
• Browser: Safari / Chrome, latest releases

➕ Additional Context

The error is preventing updates being rendered. As a result, I need to re-run ember s after each change is saved.

[bertdeblock]

@roomman Are you using Embroider? If so, you might be running into embroider-build/embroider#1211

[roomman]

@roomman Are you using Embroider?

Yes I am, thanks @bertdeblock, will close this down and roll back Embroider now. Many thanks!