Code generated for a next in a while is incorrect

[herwinw]

Given this code:

a = 3
until a.negative?
  a -= 1
  next if a == 1
  p "a = #{a}"
end

p a

Cruby has the following output:

"a = 2"
"a = 0"
"a = -1"
-1

Natalie stops as soon as the next is hit:

"a = 2"

The code generated looks like this:

env->set_line(4);
auto send_6 =  a_var.public_send(env, symbols[3]/*:==*/, Args({ Value::integer(1) }, false), nullptr, self);
Value if_result7;
if (send_6->is_truthy()) {
    return Value(NilObject::the());
    if_result7 = Value(NilObject::the());
} else {
    if_result7 = Value(NilObject::the());
}

The return in the truthy path is not what we need.