“无法在后台线程上调用ObserveForever”，无论我是否使用Dispatchers.Main或Dispatchers.IO来启动协程

Question

我要做什么

我制作了一个基于MVVM架构的天气应用程序，其中我使用GPS来获取设备位置，并将该位置传递给天气API服务以获取“天气报告”，但是由于该位置可能会改变并且用户需要再次获取新位置的天气，我将该位置包装在LiveData中并进行观察，并将其传递给API服务类。

简而言之，我将在LiveData的observeForever内部使用GlobalScope启动一个协程

WeatherNetworkAbstractionsImpl.kt

class WeatherNetworkAbstractionsImpl(
    private val weatherApiService: WeatherApiService,
    private val context: Context
) : WeatherNetworkAbstractions {

    private val _downloadedWeather = MutableLiveData<WeatherResponse>()
    override val downloadedWeather: LiveData<WeatherResponse>
        get() = _downloadedWeather

    override suspend fun fetchWeather(location: LiveData<String>) {
        try {
            location.observeForever {
                GlobalScope.launch(Dispatchers.IO) {
                    val fetchedWeather = weatherApiService.getWeather(it).await()
                    _downloadedWeather.postValue(fetchedWeather)
                }
            }
        }
        catch (e: NoConnectivityException){
            Log.e("Connectivity","No internet connection.",e)
        }
    }
}

Repository.kt

class RepositoryImpl(
    private val weatherDao: WeatherDataDao,
    private val weatherNetworkAbstractions: WeatherNetworkAbstractions,
    private val weatherLocationDao: WeatherLocationDao,
    private val recordMapperImpl: RecordMapperImpl,
    private val locationMapperImpl: LocationMapperImpl,
    private val locationProvider: LocationProvider
) : Repository {
    init {
        weatherNetworkAbstractions.downloadedWeather.observeForever {latestWeatherReports->
            persistLatestWeatherReports(latestWeatherReports, recordMapperImpl, locationMapperImpl)
        }
    }
}

我的问题是什么

我收到此错误：

无法在后台线程上调用observeForever

即使我将Dispatchers.IO更改为Dispatchers.Main，但仍然遇到相同的错误。

如何解决此问题？我是协程新手。