message: Fix WatchManager global room watchers
diff: @@ -18,11 +18,10 @@ import { SettingLevel } from "./SettingLevel";
  export type CallbackFn = (changedInRoomId: string, atLevel: SettingLevel, newValAtLevel: any) => void;
  -const IRRELEVANT_ROOM = Symbol("any room");
  +const IRRELEVANT_ROOM = String(null);
  interface RoomWatcherMap {
  - // @ts-ignore - TS wants string-only keys but we know better - https://github.com/Microsoft/TypeScript/issues/1863
  - [roomId: string | symbol]: CallbackFn[];
  + [roomId: string]: CallbackFn[];
  }
  /**
  @@ -69,7 +68,7 @@ export class WatchManager {
  if (!inRoomId) {
  // Fire updates to all the individual room watchers too, as they probably
  // care about the change higher up.
  - callbacks.push(...Object.values(roomWatchers).reduce((r, a) => [...r, ...a], []));
  + callbacks.push(...Object.values(roomWatchers).flat(1));
  } else if (roomWatchers[IRRELEVANT_ROOM]) {
  callbacks.push(...roomWatchers[IRRELEVANT_ROOM]);
  }
  