Fix prioritized slot iterator

src/main/kotlin/ru/dbotthepony/mc/otm/block/entity/storage/StorageBusBlockEntity.kt

@@ -2,8 +2,6 @@ package ru.dbotthepony.mc.otm.block.entity.storage
 
 import it.unimi.dsi.fastutil.ints.Int2ObjectAVLTreeMap
 import it.unimi.dsi.fastutil.ints.IntAVLTreeSet
-import it.unimi.dsi.fastutil.ints.IntArraySet
-import it.unimi.dsi.fastutil.longs.Long2ObjectAVLTreeMap
 import net.minecraft.core.BlockPos
 import net.minecraft.core.Direction
 import net.minecraft.nbt.CompoundTag
@@ -44,6 +42,7 @@ import java.lang.ref.WeakReference
 import java.math.BigInteger
 import java.util.*
 import java.util.stream.Stream
+import kotlin.NoSuchElementException
 import kotlin.collections.ArrayList
 import kotlin.collections.HashMap
 
@@ -251,21 +250,47 @@ class StorageBusBlockEntity(blockPos: BlockPos, blockState: BlockState) : Matter
 			private val seenIterator = tupleIndexes.iterator()
 			private val regularIterator = (0 until parent.slots).iterator()
 
+			private var storedValue = -1
+
 			override fun hasNext(): Boolean {
-				return seenIterator.hasNext() || regularIterator.hasNext()
+				return seenIterator.hasNext() || storedValue != -1
+			}
+
+			private fun advance() {
+				if (!regularIterator.hasNext()) {
+					storedValue = -1
+					return
+				}
+
+				var value = regularIterator.nextInt()
+				var removed = tupleIndexes.remove(value)
+
+				while (removed && regularIterator.hasNext()) {
+					value = regularIterator.nextInt()
+					removed = tupleIndexes.remove(value)
+				}
+
+				if (!removed) {
+					storedValue = value
+				}
 			}
 
 			override fun next(): Int {
-				if (seenIterator.hasNext())
-					return seenIterator.nextInt()
+				if (storedValue != -1) {
+					val value = storedValue
+					advance()
+					return value
+				} else if (seenIterator.hasNext()) {
+					val value = seenIterator.nextInt()
 
-				var value = regularIterator.nextInt()
+					if (!seenIterator.hasNext()) {
+						advance()
+					}
 
-				while (tupleIndexes.remove(value)) {
-					value = regularIterator.nextInt()
+					return value
 				}
 
-				return value
+				throw NoSuchElementException("Reached end of iteration")
 			}
 		}