Invalid output for ETL exercise

When submitting the following solution to the `etl` exercise:

```perl5
use experimental qw( signatures switch );

sub transform ( $data ) {

return reverse %$data;

my %result;

for my $key ( keys %$data ) {
for my $value ( %$data{ $key } ) {
$result->{ lc $value }++; # = [ $result{ lc $value }, lc $key ];
}
}

# for my $key (keys %$data) {
# %results->{ lc %$data->{$_} } = $_;
# }

return \%result;

}

use strict; use warnings;
use Exporter qw; our @EXPORT_OK = qw
```

the test runner returns invalid JSON:

```json
{
"status" : "fail",
"tests" : [
{
"name" : "Imported symbol: transform",
"output" : null,
"status" : "pass"
},
{
"message" : "+-----------------------+----+-------+\n| GOT | OP | CHECK |\n+-----------------------+----+-------+\n| ARRAY(0x5654e8335858) | eq | 1 |\n+-----------------------+----+-------+single letter",
"name" : {
"a" : 1
},
"output" : null,
"status" : "fail"
},
{
"message" : "+-----------------------+----+-------+\n| GOT | OP | CHECK |\n+-----------------------+----+-------+\n| ARRAY(0x5654e7386458) | eq | 1 |\n+-----------------------+----+-------+single score with multiple letters",
"name" : {
"a" : 1,
"e" : 1,
"i" : 1,
"o" : 1,
"u" : 1
},
"output" : null,
"status" : "fail"
},
{
"message" : "+-----------------------+----+-------+\n| GOT | OP | CHECK |\n+-----------------------+----+-------+\n| ARRAY(0x5654e79cb540) | eq | 2 |\n+-----------------------+----+-------+1HASH(0x55f9ca8e2620)multiple scores with multiple letters",
"name" : [
"A",
"E"
],
"output" : null,
"status" : "fail"
},
{
"message" : "+-----------------------+----+-------+\n| GOT | OP | CHECK |\n+-----------------------+----+-------+\n| ARRAY(0x5654e7378b50) | eq | 8 |\n+-----------------------+----+-------+2ARRAY(0x55f9ca8e2350)5ARRAY(0x55f9ca8e2a88)1ARRAY(0x55f9caad4d38)4ARRAY(0x55f9caad4c90)10ARRAY(0x55f9caad4480)3HASH(0x55f9ca8e26b0)multiple scores with differing numbers of letters",
"name" : [
"D",
"G"
],
"output" : null,
"status" : "fail"
}
],
"version" : 2
}
```

How how the `name` key is a `string`, `object` and `array`. We only accept strings for the name though, so the others likely indicate some issue with the test runner.