How to catch 404 of a custom asset loader?

[DerKarlos]

Hi! I use my own custom asset loader.
The app user may enter an non existing OSM way ID, causing a web error 404.
I would like to catch that error and only write a text in the UI, no crash please.
I can't test except info! because it runs on WASM web.
It looks like my on_load function is not even called.
There is no on_error, is there?
You may try it here: http://www.osmgo.org/bevy.html is ok.
But http://www.osmgo.org/bevy.html&way=4711 is not.
Repo: https://github.com/DerKarlos/obi/blob/master/src/bevy_ui.rs