@type t() :: %Figler.Schema.IndexFontFile{
  family: String.t() | nil,
  filename: String.t() | nil,
  styles: [Figler.Schema.IndexFontStyle.t()] | nil,
  use_font_optical_size: boolean() | nil,
  variation_axes: [Figler.Schema.IndexFontVariationAxis.t()] | nil,
  version: non_neg_integer() | nil
}