Fix empty chapters label

app/src/main/java/org/koitharu/kotatsu/utils/PausingDispatcher.kt

@@ -0,0 +1,50 @@
+package org.koitharu.kotatsu.utils
+
+import androidx.annotation.MainThread
+import java.util.concurrent.ConcurrentLinkedQueue
+import kotlin.coroutines.CoroutineContext
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.Runnable
+
+class PausingDispatcher(
+	private val dispatcher: CoroutineDispatcher,
+) : CoroutineDispatcher() {
+
+	@Volatile
+	private var isPaused = false
+	private val queue = ConcurrentLinkedQueue<Task>()
+
+	override fun isDispatchNeeded(context: CoroutineContext): Boolean {
+		return isPaused || super.isDispatchNeeded(context)
+	}
+
+	override fun dispatch(context: CoroutineContext, block: Runnable) {
+		if (isPaused) {
+			queue.add(Task(context, block))
+		} else {
+			dispatcher.dispatch(context, block)
+		}
+	}
+
+	@MainThread
+	fun pause() {
+		isPaused = true
+	}
+
+	@MainThread
+	fun resume() {
+		if (!isPaused) {
+			return
+		}
+		isPaused = false
+		while (true) {
+			val task = queue.poll() ?: break
+			dispatcher.dispatch(task.context, task.block)
+		}
+	}
+
+	private class Task(
+		val context: CoroutineContext,
+		val block: Runnable,
+	)
+}