Handle async cache in updates and manga screens

- Also fix concurrent accesses to main cache map
- Also debounce sources and updates list updates to maybe avoid crashing due to dupe LazyColumn keys

app/src/main/java/eu/kanade/tachiyomi/ui/browse/source/SourcesPresenter.kt

@@ -16,6 +16,7 @@ import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.channels.Channel
 import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.collectLatest
+import kotlinx.coroutines.flow.debounce
 import kotlinx.coroutines.flow.receiveAsFlow
 import logcat.LogPriority
 import uy.kohesive.injekt.Injekt
@@ -38,6 +39,7 @@ class SourcesPresenter(
     fun onCreate() {
         presenterScope.launchIO {
             getEnabledSources.subscribe()
+                .debounce(500) // Avoid crashes due to LazyColumn rendering
                 .catch { exception ->
                     logcat(LogPriority.ERROR, exception)
                     _events.send(Event.FailedFetchingSources)