check isAir instead of null

nms/nms-common/src/main/kotlin/xyz/alexcrea/cuanvil/dependency/util/PaperSpigotUtil.kt

@@ -57,8 +57,10 @@ object PlatformUtil {
         } else {
             val legacyLore = ArrayList<String?>(lore.size)
             for (component in lore) {
-                legacyLore.add(if(component == null) null
-                else legacy_mm.serialize(component))
+                legacyLore.add(
+                    if (component == null) null
+                    else legacy_mm.serialize(component)
+                )
             }
 
             this.lore = legacyLore
@@ -66,24 +68,23 @@ object PlatformUtil {
     }
 
     // Display name
-    private val useCustomName = hasMethod(ItemStack::class.java, "customName")
+    private val useCustomName = hasMethod(ItemMeta::class.java, "customName")
 
     fun ItemMeta.componentDisplayName(): Component? {
         if (useCustomName) {
             if (!this.hasCustomName()) return null
             return this.customName()
-        }else if(isPaper){
+        }
         if (!this.hasDisplayName()) return null
-            return this.displayName()
+
+        return if (isPaper) {
+            this.displayName()
         } else {
-            if(!this.hasDisplayName()) return null
-
-            val legacy = this.displayName
-            return legacy_mm.deserialize(legacy)
+            legacy_mm.deserialize(this.displayName)
         }
     }
 
-    fun ItemMeta.setComponentDisplayName(component: Component?) {
+    fun ItemMeta.setComponentDisplayName(component: Component?, fallback: String? = null) {
         if (useCustomName) {
             this.customName(component)
         } else if (isPaper) {
@@ -94,7 +95,7 @@ object PlatformUtil {
                 return
             }
 
-            val legacy = legacy_mm.serialize(component)
+            val legacy = fallback ?: legacy_mm.serialize(component)
             this.setDisplayName(legacy)
         }
     }

src/main/kotlin/io/delilaheve/util/ItemUtil.kt

@@ -82,6 +82,6 @@ object ItemUtil {
      * The two items should either be the same type, or, the [other] is a book
      */
     fun ItemStack.canMergeWith(
-        other: ItemStack?
-    ) = (other != null) && (customType == other.customType || (other.isEnchantedBook()))
+        other: ItemStack
+    ) = customType == other.customType || (other.isEnchantedBook())
 }

src/main/kotlin/xyz/alexcrea/cuanvil/anvil/AnvilMergeLogic.kt

@@ -6,6 +6,7 @@ import io.delilaheve.util.EnchantmentUtil.combineWith
 import io.delilaheve.util.ItemUtil.isEnchantedBook
 import io.delilaheve.util.ItemUtil.repairFrom
 import io.delilaheve.util.ItemUtil.unitRepair
+import net.kyori.adventure.text.Component
 import org.bukkit.ChatColor
 import org.bukkit.Material
 import org.bukkit.entity.HumanEntity
@@ -16,6 +17,7 @@ import org.bukkit.inventory.view.AnvilView
 import org.bukkit.persistence.PersistentDataType
 import xyz.alexcrea.cuanvil.api.EnchantmentApi
 import xyz.alexcrea.cuanvil.dependency.DependencyManager
+import xyz.alexcrea.cuanvil.dependency.util.PlatformUtil.setComponentDisplayName
 import xyz.alexcrea.cuanvil.dialog.AnvilRenameDialog
 import xyz.alexcrea.cuanvil.enchant.CAEnchantment
 import xyz.alexcrea.cuanvil.recipe.AnvilCustomRecipe
@@ -138,11 +140,12 @@ object AnvilMergeLogic {
     private fun handleRename(resultItem: ItemStack, view: AnvilView, player: HumanEntity): Int {
         // Can be null
         var renameText = ChatColor.stripColor(view.renameText)
+        var component: Component? = null
 
         var sumCost = 0
         var useColor = false
         if (ConfigOptions.renameColorPossible && renameText != null) {
-            val component = AnvilColorUtil.handleColor(
+            component = AnvilColorUtil.handleColor(
                 renameText,
                 AnvilColorUtil.renamePermission(player)
             )
@@ -169,7 +172,11 @@ object AnvilMergeLogic {
                         renameText == CasedStringUtil.snakeToUpperSpacedCase(resultItem.type.name.lowercase())
                         )
             ) {
-                it.setDisplayName(renameText)
+                if (component == null)
+                    component = if (renameText == null || renameText.isEmpty()) null
+                    else Component.text(renameText)
+                it.setComponentDisplayName(component, renameText)
+
                 processDialogPCD(it, player)
                 resultItem.itemMeta = it
 

src/main/kotlin/xyz/alexcrea/cuanvil/listener/AnvilResultListener.kt

@@ -31,6 +31,7 @@ import xyz.alexcrea.cuanvil.listener.PrepareAnvilListener.Companion.ANVIL_INPUT_
 import xyz.alexcrea.cuanvil.listener.PrepareAnvilListener.Companion.ANVIL_INPUT_RIGHT
 import xyz.alexcrea.cuanvil.listener.PrepareAnvilListener.Companion.ANVIL_OUTPUT_SLOT
 import xyz.alexcrea.cuanvil.util.CustomRecipeUtil
+import xyz.alexcrea.cuanvil.util.MaterialUtil.isAir
 import xyz.alexcrea.cuanvil.util.MiniMessageUtil
 import xyz.alexcrea.cuanvil.util.anvil.AnvilLoreEditUtil
 import xyz.alexcrea.cuanvil.util.anvil.AnvilXpUtil
@@ -92,7 +93,7 @@ class AnvilResultListener : Listener {
         }
 
         // Rename
-        if (rightItem == null) {
+        if (rightItem.isAir) {
             val result = AnvilMergeLogic.doRenaming(view, player, leftItem)
             if (result.isEmpty()) return
 
@@ -106,7 +107,7 @@ class AnvilResultListener : Listener {
         }
 
         // Merge
-        val canMerge = leftItem.canMergeWith(rightItem)
+        val canMerge = leftItem.canMergeWith(rightItem!!)
         if (canMerge) {
             val result = AnvilMergeLogic.doMerge(view, player, leftItem, rightItem)