Fix crashes

app/src/main/kotlin/org/koitharu/kotatsu/core/cache/ExpiringLruCache.kt

@@ -13,6 +13,7 @@ class ExpiringLruCache<T>(
 
 	private val cache = SieveCache<CacheKey, ExpiringValue<T>>(maxSize)
 
+	@Synchronized
 	operator fun get(key: CacheKey): T? {
 		val value = cache[key] ?: return null
 		if (value.isExpired) {
@@ -22,21 +23,28 @@ class ExpiringLruCache<T>(
 	}
 
 	operator fun set(key: CacheKey, value: T) {
-		cache.put(key, ExpiringValue(value, lifetime, timeUnit))
+		val value = ExpiringValue(value, lifetime, timeUnit)
+		synchronized(this) {
+			cache.put(key, value)
+		}
 	}
 
+	@Synchronized
 	fun clear() {
 		cache.evictAll()
 	}
 
+	@Synchronized
 	fun trimToSize(size: Int) {
 		cache.trimToSize(size)
 	}
 
+	@Synchronized
 	fun remove(key: CacheKey) {
 		cache.remove(key)
 	}
 
+	@Synchronized
 	fun removeAll(source: MangaSource) {
 		cache.removeIf { key, _ -> key.source == source }
 	}

app/src/main/kotlin/org/koitharu/kotatsu/favourites/ui/container/FavouritesContainerAdapter.kt

@@ -4,6 +4,7 @@ import androidx.fragment.app.Fragment
 import androidx.recyclerview.widget.AdapterListUpdateCallback
 import androidx.recyclerview.widget.AsyncDifferConfig
 import androidx.recyclerview.widget.AsyncListDiffer
+import androidx.recyclerview.widget.RecyclerView
 import androidx.viewpager2.adapter.FragmentStateAdapter
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.asExecutor
@@ -26,7 +27,7 @@ class FavouritesContainerAdapter(fragment: Fragment) : FragmentStateAdapter(frag
 	override fun getItemCount(): Int = differ.currentList.size
 
 	override fun getItemId(position: Int): Long {
-		return differ.currentList[position].id
+		return differ.currentList.getOrNull(position)?.id ?: RecyclerView.NO_ID
 	}
 
 	override fun containsItem(itemId: Long): Boolean {