From @zoffixznet

The error in the code is that '{' for the $y parameter is BEFORE the 'where' instead of after it. The error messages, however, show a different error​:

<Zoffix> m​: sub foo ( $x where { any <foo bar> }, $y { where 42 } ) { };
<camelia> rakudo-moar f1dd49​: OUTPUT«===SORRY!===␤Expression needs parens to avoid gobbling block␤at /tmp/zGERsntt2y​:1␤------> sub foo ( $x where { any <foo bar> }⏏, $y { where 42 } ) { };␤Missing block (apparently claimed by expression)␤at /tmp/zGERsntt2y​:1␤------>…»
<Zoffix> m​: sub foo ( $x where { 42 }, $y { where 42 } ) { };
<camelia> rakudo-moar f1dd49​: OUTPUT«===SORRY!===␤Expression needs parens to avoid gobbling block␤at /tmp/gSOsYvX4uK​:1␤------> sub foo ( $x where { 42 }⏏, $y { where 42 } ) { };␤Missing block (apparently claimed by expression)␤at /tmp/gSOsYvX4uK​:1␤------> sub foo …»