Perl nowadays have TypeScript-style type checking for function parameters.

I can't believe that.

TS code, compile time error "TS2345: Argument of type 'null' is not assignable to parameter of type 'number'."

    function foo(x: number): void {};
    foo(null);

Perl code:

    use Kavorka qw(fun);
    use Types::Standard qw(Num);
    fun foo(Num $x) {}
    foo(undef);

This code passes CHECK (perl -c), but should not if you are correct.

I invite you to prove the claim. Rewrite this with any module you like.