[perl #131490] Crash in Junction:D.BUILDALL `This type (Scalar) does not support elems`

[Sam S. via RT]

On Sat, 30 Sep 2017 13:13:31 -0700, c...@zoffix.com wrote:
> Don't see a reason why not.

Well, passing a 'type' string parameter to select between what is essentially 
different object sub-types, seems internal-ish.

I can't think of anything else in the public Perl 6 API which does this; a more 
Perl 6'ish API would dispatch based on *different* named parameters, or simply 
make the object sub-types available as separate subclasses.

So it might make sense to consider `Junction.new` as "not public API" for now, 
until this is ironed out.

> If it weren't, all fixed bugs still need a test to cover them.

Noted; Marking the ticket as TESTNEEDED.

A test for the current behavior could look like:

    use Test;
    throws-like { Junction.new }, X::Multi::NoMatch, "Junction.new with no 
arguments";