Ensure widgets are destroyed cleanly when minimized

Fixes https://github.com/vector-im/element-web/issues/15444 (an artifact of joining a call then minimizing the widget)

Also fixes other issues relating to widgets not loading when being minimized/maximized.

src/components/views/elements/AppTile.js

@@ -240,10 +240,14 @@ export default class AppTile extends React.Component {
             this.iframe.src = 'about:blank';
         }
 
+        if (WidgetType.JITSI.matches(this.props.app.type)) {
+            dis.dispatch({action: 'hangup_conference'});
+        }
+
         // Delete the widget from the persisted store for good measure.
         PersistedElement.destroyElement(this._persistKey);
 
-        this._sgWidget.stop();
+        this._sgWidget.stop({forceDestroy: true});
     }
 
     /* If user has permission to modify widgets, delete the widget,
@@ -387,6 +391,9 @@ export default class AppTile extends React.Component {
             if (this.props.show) {
                 // if we were being shown, end the widget as we're about to be minimized.
                 this._endWidgetActions();
+            } else {
+                // restart the widget actions
+                this._resetWidget(this.props);
             }
             dis.dispatch({
                 action: 'appsDrawer',

src/components/views/elements/PersistentApp.js

@@ -58,6 +58,11 @@ export default class PersistentApp extends React.Component {
             const persistentWidgetInRoomId = ActiveWidgetStore.getRoomId(this.state.persistentWidgetId);
             if (this.state.roomId !== persistentWidgetInRoomId) {
                 const persistentWidgetInRoom = MatrixClientPeg.get().getRoom(persistentWidgetInRoomId);
+
+                // Sanity check the room - the widget may have been destroyed between render cycles, and
+                // thus no room is associated anymore.
+                if (!persistentWidgetInRoom) return null;
+
                 // get the widget data
                 const appEvent = WidgetUtils.getRoomWidgets(persistentWidgetInRoom).find((ev) => {
                     return ev.getStateKey() === ActiveWidgetStore.getPersistentWidgetId();

src/stores/widgets/StopGapWidget.ts

@@ -283,8 +283,8 @@ export class StopGapWidget extends EventEmitter {
         }
     }
 
-    public stop() {
+    public stop(opts = {forceDestroy: false}) {
-        if (ActiveWidgetStore.getPersistentWidgetId() === this.mockWidget.id) {
+        if (!opts?.forceDestroy && ActiveWidgetStore.getPersistentWidgetId() === this.mockWidget.id) {
             console.log("Skipping destroy - persistent widget");
             return;
         }