In the image above, I have set default state values incorrectly (this_is_not_ok is not part of the State interface). Typescript does not seem to mind, though. One way to fix the issue was to explicitly add a type annotation.
I could also fix the issue by using a constructor():
constructor(){
super();
this.state = {spelling_error: "wrong"};
}
Why did type inference not work in the first example?