using qbootstrap, trying to rewrite EXPR_reduce in pure nqp, the commented instructions trip nqp #nqp

Grammar.nqp

class A {
    # @opd is the operand stack; @opr is the operator stack
    method EXPR_reduce(@opd, @opr) {
        my $opr     := @opr.pop();
        my %opOPER  := $opr<OPER>;
        my %opO     := %opOPER<O>;  # property hash of the operator
        my $opAssoc :=  %opO<assoc>;
        my $what;
        if $opAssoc eq 'unary' {
            my $arg := @opd.pop();
            $opr[0] := $arg;
#            $what := $arg.from() < $opr.from() ?? 'POSTFIX' !! 'PREFIX';
        } elsif  $opAssoc eq 'list' {
            my $sym := opOPER['sym'] // '';
            $opr.unshift(@opd.pop());
            while @opr { 
                my $s := @opr[@opr-1]<OPER><sym> // '';
                last if $sym eq $s;
                $opr.unshift(@opd.pop());
                @opr.pop();
            }
            $opr.unshift(@opd.pop());
            $what := 'LIST';
        } else {
            $opr[0] := @opd.pop();
            $opr[1] := @opd.pop();
            my $r := %opO<reducecheck>;
            if $r {
                my $s := ~$r;
                self."$s"($opr);
            }
            $what := 'INFIX';
        }
#        self.reduce_with_match('EXPR', $what, $opr);
        @opr.push($opr);
    }
}

any statement, (like "1;") in place of the commented ones , triggers the error message : Unable to parse blockoid, couldn't find final '}'