JS exception due to wrong variable in download function

[123swk123]

Description

nicegui/nicegui/static/nicegui.js

Line 243 in bbab081

URL.revokeObjectURL(url);

argument url should be changed to anchor.href

exception details

nicegui.js:363 ReferenceError: url is not defined
    at download (nicegui.js:244:25)
    at download (nicegui.js:348:28)
    at nicegui.js:355:41
    at a.<anonymous> (nicegui.js:361:23)
    at U.emit (index.mjs:136:20)
    at a.value (socket.js:498:20)
    at a.value (socket.js:485:18)
    at a.value (socket.js:455:22)
    at U.emit (index.mjs:136:20)
    at manager.js:204:18

[falkoschindler]

Thanks for reporting this issue, @123swk123!

Reproduction (like in this demo):

ui.button('Download', on_click=lambda: ui.download(b'Hello World', 'hello.txt'))

Looks like I introduced this bug during a code review:
9dbf8b9#diff-4e4cc16e68c714c6a8433c24c00c6bc837f4f7ed51259f6e4bff356931927ed0