Fix some inconsistency issues with empty map items (#6304)

patches/server/Fix-incosistency-issue-with-empty-map-items-in-CB.patch

@@ -0,0 +1,31 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Shane Freeder <theboyetronic@gmail.com>
+Date: Sun, 1 Aug 2021 09:49:06 +0100
+Subject: [PATCH] Fix incosistency issue with empty map items in CB
+
+
+diff --git a/src/main/java/net/minecraft/world/item/MapItem.java b/src/main/java/net/minecraft/world/item/MapItem.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/world/item/MapItem.java
++++ b/src/main/java/net/minecraft/world/item/MapItem.java
+@@ -0,0 +0,0 @@ public class MapItem extends ComplexItem {
+     public static Integer getMapId(ItemStack stack) {
+         CompoundTag nbttagcompound = stack.getTag();
+ 
+-        return nbttagcompound != null && nbttagcompound.contains("map", 99) ? nbttagcompound.getInt("map") : -1; // CraftBukkit - make new maps for no tag
++        return nbttagcompound != null && nbttagcompound.contains("map", 99) ? nbttagcompound.getInt("map") : null; // CraftBukkit - make new maps for no tag // Paper - don't return invalid ID
+     }
+ 
+     public static int createNewSavedData(Level world, int x, int z, int scale, boolean showIcons, boolean unlimitedTracking, ResourceKey<Level> dimension) {
+diff --git a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaMap.java b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaMap.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaMap.java
++++ b/src/main/java/org/bukkit/craftbukkit/inventory/CraftMetaMap.java
+@@ -0,0 +0,0 @@ class CraftMetaMap extends CraftMetaItem implements MapMeta {
+ 
+     @Override
+     public int getMapId() {
++        Preconditions.checkState(this.hasMapView(), "Item does not have map associated - check hasMapView() first!"); // Paper - more friendly message
+         return this.mapId;
+     }
+ 

patches/server/Improve-Maps-in-item-frames-performance-and-bug-fixe.patch

@@ -59,19 +59,6 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
  
              return entityitem;
          }
-diff --git a/src/main/java/net/minecraft/world/item/MapItem.java b/src/main/java/net/minecraft/world/item/MapItem.java
-index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
---- a/src/main/java/net/minecraft/world/item/MapItem.java
-+++ b/src/main/java/net/minecraft/world/item/MapItem.java
-@@ -0,0 +0,0 @@ public class MapItem extends ComplexItem {
- 
-     @Nullable
-     public static MapItemSavedData getSavedData(@Nullable Integer id, Level world) {
--        return id == null ? null : world.getMapData(MapItem.makeKey(id));
-+        return id == null || id < 0 ? null : world.getMapData(MapItem.makeKey(id)); // Paper - map ids under 0 are invalid
-     }
- 
-     @Nullable
 diff --git a/src/main/java/net/minecraft/world/level/saveddata/maps/MapItemSavedData.java b/src/main/java/net/minecraft/world/level/saveddata/maps/MapItemSavedData.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
 --- a/src/main/java/net/minecraft/world/level/saveddata/maps/MapItemSavedData.java