add missing nil support

[bkilshaw]

Added support so that the Human, Percentage, and SI modules accept nil as a value.

[danielberkompas]

Looks good, thanks! ⭐

[zorn-allovue]

@danielberkompas It might be more helpful and explicit if the functions that are accepting of these nil argument values make sure nil is defined as a valid incoming argument value in the typesepcs as well.

Personal aside, I question if it is a good idea to accept nil for these functions. If the call sites do not have confidence about their variables I'm not sure the supporting libraries should have to be so accepting of nil. I'd rather the library be explicit about only offering conversion of known Number values. 🤷‍♂️

A kind of nitpicky take, and I only offer it as an additional perspective. Thanks for the work on this library.

[bkilshaw]

@danielberkompas It might be more helpful and explicit if the functions that are accepting of these nil argument values make sure nil is defined as a valid incoming argument value in the typesepcs as well.

Personal aside, I question if it is a good idea to accept nil for these functions. If the call sites do not have confidence about their variables I'm not sure the supporting libraries should have to be so accepting of nil. I'd rather the library be explicit about only offering conversion of known Number values. 🤷‍♂️

A kind of nitpicky take, and I only offer it as an additional perspective. Thanks for the work on this library.

I honestly don't have a strong opinion either way; some of the other modules accept (and return) nil, so I was aligning the other modules so they all behaved the same. Removing the nil support in the other modules would be a breaking change though.

In our use case we're using Number directly in our HEEX templates, some fields nave a nil value, so something like this ended up being useful:

<table>
   <tr :for={quote <- quote_requests}>
      <td><%= quote.name %></td>
      <td><%= Number.Currency.number_to_currency(quote.price) %>
   </tr>
</table>

We needed the same for the Percentage module hence the PR. We can definitely check the value first, just sharing the use case for accepting nil.

[danielberkompas]

I chose to accept nil here because it matches the behavior of ActionView::NumberHelper. Since number advertises itself as having a very similar API, I think it makes sense to follow ActionView::NumberHelper, to reduce surprises that former Rails developers in particular will experience when using the library.

Thanks for the feedback both of you!

[zorn-allovue]

Thanks for the reply and the context. 👍