allow for the serializer to get the $xtra data as well

lib/Dancer2/Serializer/JsonApi.pm

@@ -25,7 +25,7 @@ sub serialize {
     my ( $self, $data ) = @_;
 
     return $self->json_serializer->serialize(
-        $self->registry->serialize(%$data) );
+        $self->registry->serialize(@$data) );
 }
 
 sub deserialize { ... }

t/serializer.t

@@ -6,7 +6,7 @@ use Dancer2::Serializer::JsonApi;
 my $serializer =
   Dancer2::Serializer::JsonApi->new( log_cb => sub { warn @_ } );
 
-my $data = { 'thing' =>, { id => 2 } };
+my $data = [ 'thing' => { id => 2 } ];
 
 my $serialized = $serializer->serialize($data);