`Uncaught Error: window.__FLUXER_BOOTSTRAP__ is missing — app must be served by fluxer_app_proxy` on selfhosted community

This seems to be caused by running the instance under a proxied domain by Cloudflare and using the "Rocket Loader" feature, which basically is for "Speeding up" websites by delaying any JS and load the UI first, this is causing a side effect for Fluxer, it's wiping all child objects under Window, including window.__FLUXER_BOOTSTRAP__ in this case. To fix this, go to https://dash.cloudflare.com/ -> Speed -> Settings and disable this; image