Heap profiler sometimes fail

gistfile1.txt

dogbert@dogbert-VirtualBox ~/repos/rakudo $ cat ~/euler-3.pl6 
# What is the largest prime factor of the number 600851475143 ?
use v6;
my $num = 600_851_475_143;
my $val = $num;
my @factors = ();
while ([*] @factors) != $num {
  push @factors, (2...*).first(-> $x { $val %% $x && $x.is-prime });
  $val = $val div @factors[*-1];
}
say @factors.max; # remove max to see all prime factors
dogbert@dogbert-VirtualBox ~/repos/rakudo $ ./perl6-m --profile --profile-kind=heap ~/euler-3.pl6
Segmentation fault (core dumped)
dogbert@dogbert-VirtualBox ~/repos/rakudo $ gdb install/bin/moar core
GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1
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Reading symbols from install/bin/moar...done.
[New LWP 32186]
[New LWP 32187]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `/home/dogbert/repos/rakudo/nqp/MoarVM/../../install/bin/moar --execname=/home/d'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x00007fe32a4d1299 in describe_refs (tc=0x248da70, ss=0x7fffc8fd9f50, st=0x24f94f8, data=0x42db728) at src/6model/reprs/MVMSpeshLog.c:69
69	        switch (body->entries[i].kind) {
[Current thread is 1 (Thread 0x7fe32af1d700 (LWP 32186))]
(gdb) bt
#0  0x00007fe32a4d1299 in describe_refs (tc=0x248da70, ss=0x7fffc8fd9f50, st=0x24f94f8, data=0x42db728) at src/6model/reprs/MVMSpeshLog.c:69
#1  0x00007fe32a57a42c in process_object (tc=0x248da70, ss=0x7fffc8fd9f50, col=0x7fffc8fd9ec0, obj=0x42db710) at src/profiler/heapsnapshot.c:338
#2  0x00007fe32a57a5ed in process_workitems (tc=0x248da70, ss=0x7fffc8fd9f50) at src/profiler/heapsnapshot.c:362
#3  0x00007fe32a57b593 in record_snapshot (tc=0x248da70, col=0x5327ad0, hs=0x52357c0) at src/profiler/heapsnapshot.c:635
#4  0x00007fe32a57c5c1 in MVM_profile_heap_take_snapshot (tc=0x248da70) at src/profiler/heapsnapshot.c:936
#5  0x00007fe32a46a534 in finish_gc (tc=0x248da70, gen=0 '\000', is_coordinator=1 '\001') at src/gc/orchestrate.c:260
#6  0x00007fe32a46a9f6 in run_gc (tc=0x248da70, what_to_do=0 '\000') at src/gc/orchestrate.c:420
#7  0x00007fe32a46af0f in MVM_gc_enter_from_allocator (tc=0x248da70) at src/gc/orchestrate.c:552
#8  0x00007fe32a46b78b in MVM_gc_allocate_nursery (tc=0x248da70, size=88) at src/gc/allocation.c:35
#9  0x00007fe32a46b586 in MVM_gc_allocate (tc=0x248da70, size=88) at src/gc/allocation.h:18
#10 0x00007fe32a46b814 in MVM_gc_allocate_zeroed (tc=0x248da70, size=88) at src/gc/allocation.c:52
#11 0x00007fe32a46b9db in MVM_gc_allocate_object (tc=0x248da70, st=0x24f9110) at src/gc/allocation.c:89
#12 0x00007fe32a48c0d6 in MVM_repr_alloc_init (tc=0x248da70, type=0x2504b80) at src/6model/reprconv.c:17
#13 0x00007fe32a453b91 in MVM_continuation_control (tc=0x248da70, protect=0, tag=0x4b54810, code=0x7fe3267322d8, res_reg=0x298d8a8) at src/core/continuation.c:83
#14 0x00007fe32a41931c in MVM_interp_run (tc=0x248da70, initial_invoke=0x7fe32a584dd6 <toplevel_initial_invoke>, invoke_data=0x256bdb8) at src/core/interp.c:3951
#15 0x00007fe32a584f4e in MVM_vm_run_file (instance=0x248d010, filename=0x7fffc8fdc180 "/home/dogbert/repos/rakudo/perl6.moarvm") at src/moar.c:445
#16 0x00000000004016e7 in main (argc=10, argv=0x7fffc8fdbc38) at src/main.c:302

dogbert@dogbert-VirtualBox ~/repos/rakudo $ ./perl6-m --profile --profile-kind=heap ~/euler-3.pl6
ASAN:SIGSEGV
=================================================================
==1150==ERROR: AddressSanitizer: SEGV on unknown address 0x00000003a4e8 (pc 0x7f4bd834f5bf bp 0x7ffd0f37e410 sp 0x7ffd0f37e3e0 T0)
    #0 0x7f4bd834f5be in describe_refs src/6model/reprs/MVMSpeshLog.c:69
    #1 0x7f4bd84c4538 in process_object src/profiler/heapsnapshot.c:338
    #2 0x7f4bd84c4a06 in process_workitems src/profiler/heapsnapshot.c:362
    #3 0x7f4bd84c6a71 in record_snapshot src/profiler/heapsnapshot.c:635
    #4 0x7f4bd84c93f9 in MVM_profile_heap_take_snapshot src/profiler/heapsnapshot.c:936
    #5 0x7f4bd824256a in finish_gc src/gc/orchestrate.c:260
    #6 0x7f4bd8242ef6 in run_gc src/gc/orchestrate.c:420
    #7 0x7f4bd8243b56 in MVM_gc_enter_from_allocator src/gc/orchestrate.c:552
    #8 0x7f4bd8245055 in MVM_gc_allocate_nursery src/gc/allocation.c:35
    #9 0x7f4bd82449d6 in MVM_gc_allocate src/gc/allocation.h:18
    #10 0x7f4bd8245132 in MVM_gc_allocate_zeroed src/gc/allocation.c:52
    #11 0x7f4bd82455bf in MVM_gc_allocate_object src/gc/allocation.c:89
    #12 0x7f4bd81c6adb in MVM_frame_takeclosure src/core/frame.c:1207
    #13 0x7f4bd8161bd7 in MVM_interp_run src/core/interp.c:1232
    #14 0x7f4bd84de93d in MVM_vm_run_file src/moar.c:445
    #15 0x40232c in main src/main.c:302
    #16 0x7f4bd76c182f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
    #17 0x401298 in _start (/home/dogbert/repos/rakudo/install/bin/moar+0x401298)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV src/6model/reprs/MVMSpeshLog.c:69 describe_refs
==1150==ABORTING

dogbert@dogbert-VirtualBox ~/repos/rakudo $ ./perl6-gdb-m --profile --profile-kind=heap ~/euler-3.pl6
================================================================================================
This is Rakudo Perl 6 running in the  debugger, which often allows the user to generate useful back-
traces to debug or report issues in Rakudo, the MoarVM backend or the currently running code.

This Rakudo version is 2019.07.1.116.g.22702.ea built on MoarVM version 2019.07.1.68.g.9.c.969.b.1,
running on linuxmint (18.3.Sylvia) / linux (42.16.04.1.Ubuntu.SMP.Tue.Oct.10.16.32.20.UTC.2017)

Type `bt full` to generate a backtrace if applicable, type `q` to quit or `help` for help.
------------------------------------------------------------------------------------------------
Reading symbols from /home/dogbert/repos/rakudo/nqp/MoarVM/../../install/bin/moar...done.
Starting program: /home/dogbert/repos/rakudo/install/bin/moar --execname=/home/dogbert/repos/rakudo/perl6-gdb-m --libpath=/home/dogbert/repos/rakudo --libpath=/home/dogbert/repos/rakudo/blib --libpath= --libpath=/home/dogbert/repos/rakudo/install/share/nqp/lib /home/dogbert/repos/rakudo/perl6.moarvm --nqp-lib=/home/dogbert/repos/rakudo/blib --profile --profile-kind=heap /home/dogbert/euler-3.pl6
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7ffff61d5700 (LWP 2790)]

Thread 1 "moar" received signal SIGSEGV, Segmentation fault.
0x00007ffff7593299 in describe_refs (tc=0x604a70, ss=0x7fffffffbf30, st=0x6704f8, data=0x2451a48) at src/6model/reprs/MVMSpeshLog.c:69
69	        switch (body->entries[i].kind) {
(gdb) p body
$1 = (MVMSpeshLogBody *) 0x2451a48
(gdb) p *body
$2 = {thread = 0x68b420, entries = 0x0, used = 16384, limit = 16384, was_compunit_bumped = 1 '\001', block_mutex = 0x0, block_condvar = 0x0, completed = 0}
(gdb)