Humanize errors

[visciang]

Improve the error "stack" trace.

defmodule Test.DataSpecs.A do
  @moduledoc false

  use DataSpecs

  @enforce_keys [:f_1]
  defstruct [:f_1]

  @type t :: %__MODULE__{
          f_1: %{a: [atom() | {integer(), term()}]},
        }
end

The following incorrect value:

%Test.DataSpecs.A{f_1: %{a: [:a, {:"BAD TYPE HERE", 1}]}}
|> Test.DataSpecs.A.load()

produce this error:

{:error,
 [
   "can't convert %Test.DataSpecs.A{f_1: %{a: [:a, {:\"BAD TYPE HERE\", 1}]}} to a %Test.DataSpecs.A{} struct",
   ["can't convert %Test.DataSpecs.A{f_1: %{a: [:a, {:\"BAD TYPE HERE\", 1}]}} to a map, bad k/v pairs: %{f_1: %{a: [:a, {:\"BAD TYPE HERE\", 1}]}}",
    []]
 ]}

While correct a bit cryptic. Should be humanized!

Ideally should report something like:

%Test.DataSpecs.A{f_1: %{a: [:a, {:"BAD TYPE HERE", 1}]}}
                                  ^
Expected an integer(), got an atom()