[perl #124073] Using wrong number of arguments in a start { ... } block in a map block doesn't always raise the correct exception

[via RT]

# New Ticket Created by  Rob Hoelz 
# Please include the string:  [perl #124073]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=124073 >


The example program (attached) invokes &worker with an incorrect number of 
parameters, but sometimes (19/100) the program locks up, and other times 
(52/100) throws the wrong exception (Type check failed in binding exception; 
expected 'Any' but got 'Mu').  29/100 times, the correct exception (Unhandled 
exception: Too few positionals passed; expected 2 arguments but got 1) is 
thrown.

I'm testing this on the JVM right now, but as can be expected, it's taking a 
lot longer.
use v6;

sub worker(Any $a, Int $b) {}

my $value = Any;

my @workers = (^2).map: {
    start { worker($value) }
};

await @workers;