为什么我无法访问打字稿中加载的对象数组中对象的属性？

问：

所以，我不能把我的思想放在这个问题上......

基本上，我在类中有一些变量和一个构造函数：

currentUser: UserModel | null = null;
currentServer: ServerModel | null = null;
serverMembers: UserModel[] = [];

constructor(
  private modalService: MdbModalService,
  private userDataProvider: UserDataProvider,
  private serverDataProvider: ServerDataProvider
) {
  this.currentUser = this.userDataProvider.getCurrentUser();

  this.serverDataProvider
    .loadServerMembers()
    .pipe(
      mergeMap((members) => from(members)),
      mergeMap((member) => this.userDataProvider.getUserById(member.id)),
      toArray(),
      tap((resolvedMembers) => {
        console.log(resolvedMembers);
        console.log(resolvedMembers[0]);
        console.log(resolvedMembers[0].userName);
        this.serverMembers = resolvedMembers;
      })
    )
    .subscribe();
}

控制台日志的输出分别为：

// console log 1
0: {id: 1, userName: 'Jeff'}
1: {id: 2, userName: 'John'}

// console log 2
{id: 1, userName: 'Jeff'}

// console log 3
undefined

问题是第三个控制台日志似乎无法读取对象属性值，即使 userName 有一个值。我的问题是到底是什么，为什么???