The error message points out that you are trying to get a .name from undefined.

When you do a - 1 when the value of a is 0, you get a negative index which itself then produces a result of undefined.

ducks now on dart
Translation Dart

input for goose may be None, so make sure you account for this type of value

We don't need dsa for this.
.map is just a transformation function.

For JavaScript of course not

All inputs will be valid.

this is useless information, it should instead say what the input will look like (or say nothing if that's already implied)

The instructions did not specify how to use the arguments appropriately.

nah

Approved.

To be fair, "big" and "straightforward" are extremely subjective terms.

Yes, that's why I'd like to see input ranges always documented. When they are not, I assume that anything should work (no overflows, bogosort doesn't time out, ...), otherwise it's not clear what is expected to work and what isn't.
Also, when not everything is specified, I start thinking about it less like about competitive programming and more like about a real world task where the input range is consistent with the story.

To be fair, "big" and "straightforward" are extremely subjective terms. However, out of consideration for the 8kyu level, I've forked my translation here to limit the random inputs to the same range as the other translations (except PHP).

(edit) I've also updated the description to add the input range for random tests (in all languages but PHP).

The input range isn't specified and the nature of the problem suggests than the input is small.
Haskell has big numbers in the random tests, the most straightforward solution times out.

Approved

Haskell translation

Thanks for your comment. The sample tests are static/hard coded. They'll always become outdated. and sorry for the indexing :)