TypeScript Version: 4.1.0-dev.20200917

Search Terms:
symbol class member uninitialized

Code

const Foo = Symbol()

class WithFoo {
  [Foo]: any[]; // this shouldn't be allowed without an initialization in a constructor
  Foo: any[]; // compare with this, which errors as expected
}

console.log(new WithFoo()[Foo].length) // uncaught uninitialized symbol member, oops

Expected behavior:
An error like Property 'Foo' has no initializer and is not definitely assigned in the constructor should also be emitted for the symbolic property Foo.

Actual behavior:
No such error is thrown.

Playground Link:
here