[perl #130568] [CONC] Hyper method causes process to sleep and does not return correct value

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# New Ticket Created by  RainbowZephyr 
# Please include the string:  [perl #130568]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=130568 >


perl6 --version:
This is Rakudo version 2016.12 built on MoarVM version 2016.12

OS: Arch Linux using GCC compiler and MoarVM

Using .hyper on an array sometimes returns a result and most of the 
times it does not. Additionally using .hyper may cause the entire 
process to sleep and no output returns.

Code:

use experimental :pack;

my $file = slurp("pic.png", :bin);
my $start = 8;
my $end = 11;
my $len = 0;
my $header = "";

my $data = "";
while $end <= $file.bytes {
    $len = :16(Blob.new($file[$start..$end]).unpack("H*")) ;
    $header = Blob.new($file[$start+4..$end+4]).unpack("H*");

        #!!!!!!!!!!!!!!!!!Problem is here!!!!!!!!!!!!!!!!!
  $data = $file[$start+8 ..$start+8+$len].hyper.map({$_ 
.fmt('%02x')}).list;

    say $data;
    $start = $start + $len + 12 ;
    $end = $start + 3;
}



expected output (Omitting .hyper and using only first 3 lines of 
output):
(00 00 01 85 00 00 02 6c 08 06 00 00 00 12)
(08 08 08 08 7c)
(53 6f 66 74 77 61 72 65 00 67 6e 6f 6d 65 2d 73 63 72 65 65 6e 73 68 
6f 74 ef)

actual output:
()
()
()
*process sleeps here*