$ perl6-j -e 'my int $i = 1; my $alias := $i; $alias++; say $i'
Unhandled exception: Expected a native int argument for '$a'
in print_exception (gen/jvm/CORE.setting:13633)
in <anon> (gen/jvm/CORE.setting:13674)
in command_eval (gen/jvm/stage2/NQPHLL.nqp:1287)
in command_eval (src/Perl6/Compiler.nqp:17)
in command_line (gen/jvm/stage2/NQPHLL.nqp:1227)
in MAIN (gen/jvm/main.nqp:39)
in <mainline> (gen/jvm/main.nqp:35)
in (gen/jvm/main.nqp)