Accumulate case class mapping errors instead of fail-fast

[geoffjohn11]

No description provided.

[BalmungSan]

A couple of suggestions. But, in general great work!

I would like to explore if it would be possible to avoid the noise of adding all those errors everywhere, maybe only the HList mapper should be checking if the previous exception was a MultipleIncoercibleException and if so, add a new one?
Or, you may convenience me that it may be useful for other types to report multiple errors.

[BalmungSan]

I would format it like:

decodedHead match {
  case Left(th) =>
     tail.to(convertedValue, typeHint, th :: errors).map(t => labelled.field[K](null.asInstanceOf[H]) :: t)

  case Right(v) =>
    tail.to(convertedValue, typeHint, errors).map(t => labelled.field[K](v) :: t)
}

Also, both null and asInstanceOf are code smells.
There should be a better way to make it typecheck.

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(I will try to play with the code on an editor to understand why you did that, but that will probably take me a couple of days)

[BalmungSan]

I believe that default value is not needed at all.
Apply to all the following ones.