HexToArrayError should not wrap HexToBytesError

[Kixunil]

HexToBytesError contains odd length variant which is unreachable when parsing array - it's just invalid length.

We should put invalid char directly into HexToArrayError and panic during conversion if necessary.

[tcharding]

I agree that the issue is correct but posit that the current code is still technically correct. If fixing as suggested makes the generics any more complicated than they already are then I think it should be left as is.

[Kixunil]

I don't see how it has anything to do with generics. Just modify the variants of the enum and panic during conversion. Unless you want to avoid the panic but we can still do that without complicating the public API by calling into an inner function after checking the length which only returns errors for invalid characters.

[tcharding]

As I suspected this issue is curly. I've had a bunch of goes at it. I am sick right now though.

[tankyleo]

@tcharding I think we can close this issue - it was fixed in #80

[tcharding]

Mad, thanks.