Example web_sys/file_upload fails to build with wasm-pack

[loewenheim]

After fixing two small problems (see #1088), running wasm-pack build in examples/web_sys/file_upload results in

error[E0308]: mismatched types
  --> web_sys/file_upload/src/lib.rs:52:67
   |
52 | ...                   self.reader.read_file_by_chunks(file, callback, 10).unwrap()
   |                                                             ^^^^^^^^ expected enum `std::option::Option`, found enum `yew::services::reader::FileChunk`
   |
   = note: expected struct `yew::callback::Callback<std::option::Option<yew::services::reader::FileChunk>>`
              found struct `yew::callback::Callback<yew::services::reader::FileChunk>`

The type of read_file_by_chunks was changed in d38ce42. I haven’t tried to compile it, but the corresponding std-web example seems to have the exact same problem. Unfortunately, I can’t easily tell what the fix would be.

Environment:

• Yew version: master

Questionnaire

• I'm interested in fixing this myself but don't know where to start
• I would like to fix and I have a solution
• I don't have time to fix this right now, but maybe later

[teymour-aldridge]

What happens if you wrap callback in a Some?

[loewenheim]

That gives me an Option<Callback<FileChunk>> instead of a Callback<Option<FileChunk>>.

[teymour-aldridge]

I think the problem is that the closure passed as the callback argument takes needs to take a parameter of type Option<FileChunk> but currently only takes an parameter of type FileChunk.

[jstarry]

This has been fixed here: #1092