无法从ViewModel向用户显示协程错误消息

class MyViewModel : ViewModel() {
    private val errorMessage = MutableLiveData<String>()

    fun getErrorMessage(): LiveData<String> {
        return errorMessage
    }

    fun doAsyncOperation() {
        viewModelScope.launch {
            try {
                // 异步操作
            } catch (e: Exception) {
                errorMessage.value = e.message
            }
        }
    }
}

class MyActivity : AppCompatActivity() {
    private lateinit var viewModel: MyViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_my)

        viewModel = ViewModelProvider(this).get(MyViewModel::class.java)

        viewModel.getErrorMessage().observe(this, Observer { errorMessage ->
            // 更新界面显示错误消息
            showErrorDialog(errorMessage)
        })

        // 执行异步操作
        viewModel.doAsyncOperation()
    }

    private fun showErrorDialog(errorMessage: String) {
        // 显示错误消息对话框
    }
}