message: Add more logging to settings watchers
  To try and track leaks versus spam.
  Fixes (it's not leaking, probably)
diff: @@ -145,7 +145,7 @@ export default class SettingsStore {
  callbackFn(originalSettingName, changedInRoomId, atLevel, newValAtLevel, newValue);
  };
  - console.log(`Starting watcher for ${settingName}@${roomId || '<null room>'}`);
  + console.log(`Starting watcher for ${settingName}@${roomId || '<null room>'} as ID ${watcherId}`);
  SettingsStore._watchers[watcherId] = localizedCallback;
  defaultWatchManager.watchSetting(settingName, roomId, localizedCallback);
  @@ -159,8 +159,12 @@ export default class SettingsStore {
  * to cancel.
  */
  static unwatchSetting(watcherReference) {
  - if (!SettingsStore._watchers[watcherReference]) return;
  + if (!SettingsStore._watchers[watcherReference]) {
  + console.warn(`Ending non-existent watcher ID ${watcherReference}`);
  + return;
  + }
  + console.log(`Ending watcher ID ${watcherReference}`);
  defaultWatchManager.unwatchSetting(SettingsStore._watchers[watcherReference]);
  delete SettingsStore._watchers[watcherReference];
  }
  