Fix page loading retry

app/src/main/kotlin/org/koitharu/kotatsu/reader/domain/PageLoader.kt

@@ -34,6 +34,7 @@ import org.koitharu.kotatsu.core.prefs.AppSettings
 import org.koitharu.kotatsu.core.util.FileSize
 import org.koitharu.kotatsu.core.util.RetainedLifecycleCoroutineScope
 import org.koitharu.kotatsu.core.util.ext.ensureSuccess
+import org.koitharu.kotatsu.core.util.ext.getCompletionResultOrNull
 import org.koitharu.kotatsu.core.util.ext.isNotEmpty
 import org.koitharu.kotatsu.core.util.ext.isPowerSaveMode
 import org.koitharu.kotatsu.core.util.ext.printStackTraceDebug
@@ -222,12 +223,9 @@ class PageLoader @Inject constructor(
 	}
 
 	private fun Deferred<File>.isValid(): Boolean {
-		return if (isCompleted) {
-			val file = getCompleted()
+		return getCompletionResultOrNull()?.map { file ->
 			file.exists() && file.isNotEmpty()
-		} else {
-			true
-		}
+		}?.getOrDefault(false) ?: true
 	}
 
 	private class InternalErrorHandler : AbstractCoroutineContextElement(CoroutineExceptionHandler),

app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/pager/PageHolderDelegate.kt

@@ -16,6 +16,7 @@ import kotlinx.coroutines.flow.launchIn
 import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.plus
+import kotlinx.coroutines.yield
 import org.koitharu.kotatsu.core.exceptions.resolve.ExceptionResolver
 import org.koitharu.kotatsu.core.os.NetworkState
 import org.koitharu.kotatsu.core.util.ext.printStackTraceDebug
@@ -137,12 +138,13 @@ class PageHolderDelegate(
 		state = State.LOADING
 		error = null
 		callback.onLoadingStarted()
+		yield()
 		try {
 			val task = loader.loadPageAsync(data, force)
 			file = coroutineScope {
 				val progressObserver = observeProgress(this, task.progressAsFlow())
 				val file = task.await()
-				progressObserver.cancel()
+				progressObserver.cancelAndJoin()
 				file
 			}
 			state = State.LOADED

app/src/main/kotlin/org/koitharu/kotatsu/reader/ui/pager/standard/PageHolder.kt

@@ -116,7 +116,7 @@ open class PageHolder(
 		bindingInfo.progressBar.hide()
 	}
 
-	override fun onClick(v: View) {
+	final override fun onClick(v: View) {
 		when (v.id) {
 			R.id.button_retry -> delegate.retry(boundData?.toMangaPage() ?: return)
 			R.id.button_error_details -> delegate.showErrorDetails(boundData?.url)