Attached 'backtrace-original.txt' is the output from the added CATCH and --ll-exception.
I was able to golf it down to this: await do for 3¹²³⁴⁵ … 3¹²³⁴⁵+127 -> $num { start $num.is-prime ?? "$num is prime" !! "$num is not prime";; } CATCH { .backtrace.full.say } And that backtrace is also attached (backtrace-golfed.txt). I tried replacing .is-prime with a bcrypt hashing, but was unable to produce the crash in about 8 runs: use Crypt::Bcrypt; await do for 3¹²³⁴⁵ … 3¹²³⁴⁵+127 -> $num { start bcrypt-hash ~$num, :15rounds; } CATCH { .backtrace.full.say } So then I went back to my golfed version and removed the ternary operator... Couldn't reproduce anything in about 10 runs. Added a ternary as `?? 1 !! 2`, still couldn't reproduce anything, Changed the ternary to this: await do for 3¹²³⁴⁵ … 3¹²³⁴⁵+127 -> $num { start $num.is-prime ?? "$num is this" !! "$num is that"; } CATCH { .backtrace.full.say } ... and it crashed the first time I ran it (backtrace-changed-ternary.txt attached) and then 1 more time in the next out of 7 runs. It may of course be just a coincidence, but these are my results
in method throw at gen/moar/m-CORE.setting line 24125 in method result at gen/moar/m-CORE.setting line 35512 in sub await at gen/moar/m-CORE.setting line 37569 in block at gen/moar/m-CORE.setting line 37568 in block at gen/moar/m-CORE.setting line 4845 in method sink-all at gen/moar/m-CORE.setting line 4831 in method sink at gen/moar/m-CORE.setting line 14540 in block <unit> at test.p6 line 1 Cannot invoke this object (REPR: Null; VMNull) at gen/moar/m-CORE.setting:24125 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:throw) from gen/moar/m-CORE.setting:35512 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:result) from gen/moar/m-CORE.setting:37569 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:await) from gen/moar/m-CORE.setting:37568 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:) from gen/moar/m-CORE.setting:4845 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:) from gen/moar/m-CORE.setting:4831 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:sink-all) from gen/moar/m-CORE.setting:14540 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:sink) from test.p6:1 (<ephemeral file>:<unit>) from test.p6:1 (<ephemeral file>:<unit-outer>) from gen/moar/stage2/NQPHLL.nqp:1519 (/home/cpan/.rakudobrew/moar-nom/install/share/nqp/lib/NQPHLL.moarvm:eval) from gen/moar/stage2/NQPHLL.nqp:1722 (/home/cpan/.rakudobrew/moar-nom/install/share/nqp/lib/NQPHLL.moarvm:evalfiles) from gen/moar/stage2/NQPHLL.nqp:1616 (/home/cpan/.rakudobrew/moar-nom/install/share/nqp/lib/NQPHLL.moarvm:command_eval) from src/Perl6/Compiler.nqp:27 (/home/cpan/.rakudobrew/moar-nom/install/share/nqp/lib/Perl6/Compiler.moarvm:command_eval) from gen/moar/stage2/NQPHLL.nqp:1590 (/home/cpan/.rakudobrew/moar-nom/install/share/nqp/lib/NQPHLL.moarvm:command_line) from gen/moar/m-main.nqp:47 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/perl6.moarvm:MAIN) from gen/moar/m-main.nqp:38 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/perl6.moarvm:<mainline>) from <unknown>:1 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/perl6.moarvm:<main>) from <unknown>:1 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/perl6.moarvm:<entry>)
cpan@perlbuild2:/tmp/tmp.AY07p77AqM$ RAKUDO_MAX_THREADS=40 perl6 --ll-exception test.p6 in method throw at gen/moar/m-CORE.setting line 24125 in method result at gen/moar/m-CORE.setting line 35512 in sub await at gen/moar/m-CORE.setting line 37569 in block at gen/moar/m-CORE.setting line 37568 in block at gen/moar/m-CORE.setting line 4845 in method sink-all at gen/moar/m-CORE.setting line 4831 in method sink at gen/moar/m-CORE.setting line 14540 in block <unit> at test.p6 line 1 Cannot invoke this object (REPR: Null; VMNull) at gen/moar/m-CORE.setting:24125 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:throw) from gen/moar/m-CORE.setting:35512 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:result) from gen/moar/m-CORE.setting:37569 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:await) from gen/moar/m-CORE.setting:37561 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:await) from gen/moar/m-CORE.setting:37568 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:) from gen/moar/m-CORE.setting:4845 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:) from gen/moar/m-CORE.setting:4831 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:sink-all) from gen/moar/m-CORE.setting:14540 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:sink) from test.p6:1 (<ephemeral file>:<unit>) from test.p6:1 (<ephemeral file>:<unit-outer>) from gen/moar/stage2/NQPHLL.nqp:1519 (/home/cpan/.rakudobrew/moar-nom/install/share/nqp/lib/NQPHLL.moarvm:eval) from gen/moar/stage2/NQPHLL.nqp:1722 (/home/cpan/.rakudobrew/moar-nom/install/share/nqp/lib/NQPHLL.moarvm:evalfiles) from gen/moar/stage2/NQPHLL.nqp:1616 (/home/cpan/.rakudobrew/moar-nom/install/share/nqp/lib/NQPHLL.moarvm:command_eval) from src/Perl6/Compiler.nqp:27 (/home/cpan/.rakudobrew/moar-nom/install/share/nqp/lib/Perl6/Compiler.moarvm:command_eval) from gen/moar/stage2/NQPHLL.nqp:1590 (/home/cpan/.rakudobrew/moar-nom/install/share/nqp/lib/NQPHLL.moarvm:command_line) from gen/moar/m-main.nqp:47 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/perl6.moarvm:MAIN) from gen/moar/m-main.nqp:38 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/perl6.moarvm:<mainline>) from <unknown>:1 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/perl6.moarvm:<main>) from <unknown>:1 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/perl6.moarvm:<entry>)
cpan@perlbuild2:/tmp/tmp.AY07p77AqM$ RAKUDO_MAX_THREADS=40 perl6 --ll-exception test.p6 Cannot invoke this object (REPR: Null; VMNull) at gen/moar/m-CORE.setting:24125 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:throw) from gen/moar/m-CORE.setting:35512 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:result) from gen/moar/m-CORE.setting:37569 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:await) from gen/moar/m-CORE.setting:37568 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:) from gen/moar/m-CORE.setting:4800 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:push-all) from gen/moar/m-CORE.setting:2681 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:push-until-lazy) from gen/moar/m-CORE.setting:16050 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:reify-until-lazy) from gen/moar/m-CORE.setting:17095 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:join) from gen/moar/m-CORE.setting:16314 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:Str) from gen/moar/m-CORE.setting:1345 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:Str) from gen/moar/m-CORE.setting:14512 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:Str) from gen/moar/m-CORE.setting:1345 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:Str) from gen/moar/m-CORE.setting:29905 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:print) from gen/moar/m-CORE.setting:29901 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/CORE.setting.moarvm:print) from test.p6:9 (<ephemeral file>:<unit>) from test.p6:1 (<ephemeral file>:<unit-outer>) from gen/moar/stage2/NQPHLL.nqp:1519 (/home/cpan/.rakudobrew/moar-nom/install/share/nqp/lib/NQPHLL.moarvm:eval) from gen/moar/stage2/NQPHLL.nqp:1722 (/home/cpan/.rakudobrew/moar-nom/install/share/nqp/lib/NQPHLL.moarvm:evalfiles) from gen/moar/stage2/NQPHLL.nqp:1616 (/home/cpan/.rakudobrew/moar-nom/install/share/nqp/lib/NQPHLL.moarvm:command_eval) from src/Perl6/Compiler.nqp:27 (/home/cpan/.rakudobrew/moar-nom/install/share/nqp/lib/Perl6/Compiler.moarvm:command_eval) from gen/moar/stage2/NQPHLL.nqp:1590 (/home/cpan/.rakudobrew/moar-nom/install/share/nqp/lib/NQPHLL.moarvm:command_line) from gen/moar/m-main.nqp:47 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/perl6.moarvm:MAIN) from gen/moar/m-main.nqp:38 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/perl6.moarvm:<mainline>) from <unknown>:1 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/perl6.moarvm:<main>) from <unknown>:1 (/home/cpan/.rakudobrew/moar-nom/install/share/perl6/runtime/perl6.moarvm:<entry>)