REFACTOR: Remove Discourse constant from get-owner

app/assets/javascripts/discourse-common/addon/lib/get-owner.js

@@ -1,14 +1,20 @@
 import deprecated from "discourse-common/lib/deprecated";
-import { getOwner as emberGetOwner } from "@ember/application";
+import { getOwner as emberGetOwner, setOwner } from "@ember/application";
+
+let _default = {};
 
 export function getOwner(obj) {
   if (emberGetOwner) {
-    return emberGetOwner(obj) || Discourse.__container__;
+    return emberGetOwner(obj) || emberGetOwner(_default);
   }
 
   return obj.container;
 }
 
+export function setDefaultOwner(container) {
+  setOwner(_default, container);
+}
+
 // `this.container` is deprecated, but we can still build a container-like
 // object for components to use
 export function getRegister(obj) {

app/assets/javascripts/discourse/app/mixins/singleton.js

@@ -82,6 +82,7 @@ const Singleton = Mixin.create({
 
   resetCurrent(val) {
     this._current = val;
+    return val;
   }
 });
 

app/assets/javascripts/discourse/app/pre-initializers/discourse-bootstrap.js

@@ -14,6 +14,7 @@ import { setIconList } from "discourse-common/lib/icon-library";
 import { setPluginContainer } from "discourse/lib/plugin-api";
 import { setURLContainer } from "discourse/lib/url";
 import { setModalContainer } from "discourse/lib/show-modal";
+import { setDefaultOwner } from "discourse-common/lib/get-owner";
 
 export default {
   name: "discourse-bootstrap",
@@ -23,6 +24,7 @@ export default {
     setPluginContainer(container);
     setURLContainer(container);
     setModalContainer(container);
+    setDefaultOwner(container);
 
     // Our test environment has its own bootstrap code
     if (isTesting()) {