Inconsistent behavior a class not being readonly if it is inside a module

[webbiesdk]

TypeScript Version: 2.3.4

Code

module Bar {
    export class Foo {
        bla = 123;
    }
}

class Foo {
    bla = 123;
}

Bar.Foo = Foo; // no error
Foo = Bar.Foo; // error: "Cannot assign to 'Foo' because it is not a variable.

Expected behavior:
Either both of the last two lines to report an error, or none of them.

Actual behavior:
It is only an error to replace a class, if it is not inside a module.

[DanielRosenwasser]

We should discuss what the "correct" behavior is.

[webbiesdk]

Modules and functions inside modules have the same behavior.

I think the "correct" behavior should be to have an error in both cases, since it seems unlikely that a programmer intends to overwrite a class/module definition.
You can always cast to any if you really want to do it.

See #17502.