LEAVE trap (my $x = …; LEAVE $x.foo)

[AlexDaniel]

It is a fairly common mistake.

Basically, code like this is wrong:

my $x = 42;
LEAVE say $x.Int; # ← WRONG; assumes that $x is not Nil

This is true even if $x is defined at the start of the block.

For example:

sub foo($ where ‘abc’) {
    my $x = 42;
    LEAVE say $x.Int; # ← WRONG; assumes that $x is not Nil
}
say foo ‘hello’; # OUTPUT: «No such method 'Int' for invocant of type 'Any'␤»

[smls]

Are you sure that this is not a Rakudo bug?
Why does the phaser run even though the subroutine's signature didn't match?

[AlexDaniel]

It could be, but generally assuming that LEAVE $foo.bar will work is a common trap.