Delegation fails with "Cannot invoke this object" when this package is used

TestD.pm6

unit package TestD;

role R {
    method foo( --> Int ) { ... }
}

class C {
    has R $.delegate
        handles *
        is required;
}

class D does R {
    has Int $.foo;
}

Place file in ./lib, run command:

$ perl6 -Ilib -MTestD -e 'my $d = TestD::D.new(:foo(2)); my $c = TestD::C.new(delegate => $d); say $d.foo; say $c.foo'
2
Cannot invoke this object (REPR: Null; VMNull)
 in block <unit> at -e line 1

The one-liner version works fine:

$ perl6 -e 'package TestD { role R { method foo(-->Int) {...} }; class C { has R $.delegate handles * is required; }; class D does R { has Int $.foo; }; }; my $d = TestD::D.new(:foo(2)); my $c = TestD::C.new(delegate => $d); say $d.foo; say $c.foo'
2
2