How do I fix Default Property warnings and errors with Fortnite?

Default Property warnings and errors:
Error: CDO Constructor: Failed to find
MaterialInstanceConstant'/Game/Materials/Decals/MI_circle.MI_circle'

If you are seeing an error message similar to the above, it may be fixed by installing the Unreal Engine with Editor symbols for debugging:

1. Open the Epic Games Launcher.
2. Click on Unreal Engine.
3. Click on the plus sign and click on Install next to the latest version of the Unreal Engine.
4. Click on Options.
5. Check the box next to Editor symbols for debugging.
6. Click on Apply.
7. Click on Install.
8. After the Unreal Engine is done installing, try to launch Fortnite.