@rx.event(background=True) is not supported for upload handler

[EssamWisam]

Describe the bug
The code:

    @rx.event(background=True)
    async def handle_upload(self, files: list[rx.UploadFile]):
        async with self:
            self.uploading = True

        for file in files:
            # Schedule reading the file as a task
            upload_data = await file.read()

            outfile = Path(self.uploads_folder) / file.filename
            outfile.parent.mkdir(parents=True, exist_ok=True)

            with outfile.open("wb") as file_object:
                file_object.write(upload_data)

            # Do some preprocessing (removed)

        async with self:
            self.uploading = False

Along with:

 rx.upload(
            rx.cond(
                State.uploading,
                rx.spinner(),
                rx.button(
                    rx.icon(tag="upload", size=19),
                    class_name="bg-accent-9 hover:bg-accent-10 p-1.5 rounded-full transition-colors cursor-pointer",
                ),
            ),
            id="file_upload",
            class_name="flex items-center",
            on_drop=State.handle_upload(rx.upload_files(upload_id="file_upload")),
            style={
                "padding": "0 !important",
                "border": "none",
            },  # Ensure no extra margin
        ),

Results in the error:

raise UploadTypeError(
reflex.utils.exceptions.UploadTypeError: @rx.event(background=True) is not supported for upload handler `reflex___state____state.frontend___state____state.handle_upload`.

To Reproduce
Copy-paste the examples above

Expected behavior
Should work as indicated in the docs here https://reflex.dev/docs/events/background-events/. The page for uploading provides a method to track upload progress but here I am looking for uploading + preprocessing progress (just a boolean to now if its still going on).

Specifics (please complete the following information):

• Python Version: 0.6.8
• Reflex Version: 3.10
• OS: Mac OS
• Browser (Optional): Edge

[linear]

ENG-5103 @rx.event(background=True) is not supported for upload handler

[EssamWisam]

Just put yield after state.uploading = ... and drop the async with self and background=True.