Is this a bug report?

Yes

Can you also reproduce the problem with npm 4.x?

Yes

Environment

1. npm ls react-scripts-ts (if you haven’t ejected): react-scripts-ts@2.16.0
2. node -v: v8.11.3
3. npm -v: 6.2.0 (I also tried with 4.x)

Then, specify:

1. Operating system: Windows 10
2. Browser and version (if relevant):

Steps to Reproduce

(Write your steps here:)

1. create-react-app my-app --scripts-version=react-scripts-ts
2. cd my-app/
3. npm start
4. Go to localhost, and I see an error :

'Interface 'Element' cannot simultaneously extend types 'ReactElement<any>' and 'ReactElement<any>'.
  Named property 'type' of types 'ReactElement<any>' and 'ReactElement<any>' are not identical.'

I don't really know what to do, I'm kinda stuck right there. I tried to delete node_modules and package.lock.json and redo a fresh install, but it didn't change anything :/.

I hope someone got an idea.