Enable lint rules for Promise handling to discourage misuse of them. (#2607)

* Enable lint rules for Promise handling to discourage misuse of them.
Squashed all of Hugh's commits into one.

---------

Co-authored-by: Hugh Nimmo-Smith <hughns@element.io>

src/rtcSessionHelpers.ts

@@ -74,8 +74,7 @@ async function makePreferredLivekitFoci(
       `No livekit_service_url is configured so we could not create a focus.
     Currently we skip computing a focus based on other users in the room.`,
     );
-
-  return preferredFoci;
+  return Promise.resolve(preferredFoci);
 
   // TODO: we want to do something like this:
   //
@@ -119,13 +118,18 @@ const widgetPostHangupProcedure = async (
   // we need to wait until the callEnded event is tracked on posthog.
   // Otherwise the iFrame gets killed before the callEnded event got tracked.
   await new Promise((resolve) => window.setTimeout(resolve, 10)); // 10ms
-  widget.api.setAlwaysOnScreen(false);
   PosthogAnalytics.instance.logout();
 
+  try {
+    await widget.api.setAlwaysOnScreen(false);
+  } catch (e) {
+    logger.error("Failed to set call widget `alwaysOnScreen` to false", e);
+  }
+
   // We send the hangup event after the memberships have been updated
   // calling leaveRTCSession.
   // We need to wait because this makes the client hosting this widget killing the IFrame.
-  widget.api.transport.send(ElementWidgetActions.HangupCall, {});
+  await widget.api.transport.send(ElementWidgetActions.HangupCall, {});
 };
 
 export async function leaveRTCSession(