TypeError: Discourse._registerPluginCode is not a function

[amotl (Andreas Motl)]

Thanks @vinothkannans for getting back and for pointing us to @sam’s comment. After following this to JavaScript not loading on certain pages and drilling down a bit further we would like to share our findings.

When looking at the Discourse object, it tells us it’s pretty much empty:

» Discourse
» > Object { SiteSettings: {} }

While the origin of this pretty much void object pretending to be a real Discourse instance

const Discourse = {
  SiteSettings: {}
}

is yet unknown, it will easily sneak through some safeguards the Discourse plugin loader had put into place, so

if ('Discourse' in window) { 
  Discourse._registerPluginCode('0.8', function (api) {
    // [...]
  }
}

would obviously be completely clueless about this and will just attempt to run the plugin registration right away as if nothing happened, ultimately croaking there.