Fix array indexes in generated classes

[dnicolson]

Before:

InnertubeError: DecoratedAvatarView not found!
This is a bug, want to help us fix it? Follow the instructions at https://github.com/LuanRT/YouTube.js/blob/main/docs/updating-the-parser.md or report it at https://github.com/LuanRT/YouTube.js/issues!
Introspected and JIT generated this class in the meantime:
class DecoratedAvatarView extends YTNode {

...
          sources: {
            0: {
              url: data.avatar.avatarViewModel.image.sources.0.url,
              width: data.avatar.avatarViewModel.image.sources.0.width,
              height: data.avatar.avatarViewModel.image.sources.0.height
            },

After:

          sources: {
            0: {
              url: data.avatar.avatarViewModel.image.sources[0].url,
              width: data.avatar.avatarViewModel.image.sources[0].width,
              height: data.avatar.avatarViewModel.image.sources[0].height

[absidue]

This doesn't fully fix the issue, as sources is created as an object instead of array. It's probably better if you add proper support for arrays, instead of abusing the fallback handlers.