Actually I upgraded this morning the typescript version (4.1.2 from 4.0.5).

I got this error :

Error: The Angular Compiler requires TypeScript >=4.0.0 and <4.1.0 but 4.1.2 was found instead.

I found the peerDependencie problem :
https://github.com/angular/angular/blob/master/packages/compiler-cli/package.json

Is it possible to plan an upgrade ?