Ensure POI removal occurs on the correct thread

Spigot-Server-Patches/0648-Remove-stale-POIs.patch

@@ -25,21 +25,24 @@ index b926cebd053bef829517c9d9bbf1c609c23ca04a..6a0f07b13eef5560dfc7c7b39618c0b8
          return (Boolean) this.d(SectionPosition.a(blockposition).s()).map((villageplacesection) -> {
              return villageplacesection.a(blockposition, predicate);
 diff --git a/src/main/java/net/minecraft/server/WorldServer.java b/src/main/java/net/minecraft/server/WorldServer.java
-index 5b0b6edfa790918e56399ff6c83f3feb6e5aca49..9b6dbadcbae284e089e38b21b596d78624d48ddd 100644
+index 5b0b6edfa790918e56399ff6c83f3feb6e5aca49..b033ff44373ec87702946c3cefe664fb46d609f4 100644
 --- a/src/main/java/net/minecraft/server/WorldServer.java
 +++ b/src/main/java/net/minecraft/server/WorldServer.java
-@@ -1942,6 +1942,10 @@ public class WorldServer extends World implements GeneratorAccessSeed {
+@@ -1942,6 +1942,13 @@ public class WorldServer extends World implements GeneratorAccessSeed {
          Optional<VillagePlaceType> optional = VillagePlaceType.b(iblockdata);
          Optional<VillagePlaceType> optional1 = VillagePlaceType.b(iblockdata1);
  
 +        // Paper start
-+        if (!optional.isPresent() && this.getPoiStorage().test(blockposition, com.google.common.base.Predicates.alwaysTrue()))
++        this.getMinecraftServer().execute(() -> {
++                if (!optional.isPresent() && this.getPoiStorage().test(blockposition, com.google.common.base.Predicates.alwaysTrue())) {
 +                    this.getPoiStorage().remove(blockposition);
++                }
++        });
 +        // Paper end
          if (!Objects.equals(optional, optional1)) {
              BlockPosition blockposition1 = blockposition.immutableCopy();
  
-@@ -1960,6 +1964,7 @@ public class WorldServer extends World implements GeneratorAccessSeed {
+@@ -1960,6 +1967,7 @@ public class WorldServer extends World implements GeneratorAccessSeed {
          }
      }