Fix loop risk in mob spawning around unloaded chunks

When a mob was about to load a chunk to try to spawn in, we did not
increment the attempt counter, resulting in it being stuck in the mob
spawn loop for a long time and hanging servers.

Spigot-Server-Patches/0369-Prevent-mob-spawning-from-loading-generating-chunks.patch

@@ -1,31 +1,34 @@
-From d25983b197588722513fd00867c2f83fdec9f682 Mon Sep 17 00:00:00 2001
+From c3d2e0dd50ede77e547a3559419b45217c93afcb Mon Sep 17 00:00:00 2001
 From: Aikar <aikar@aikar.co>
 Date: Wed, 12 Sep 2018 21:12:57 -0400
 Subject: [PATCH] Prevent mob spawning from loading/generating chunks
 
 
 diff --git a/src/main/java/net/minecraft/server/SpawnerCreature.java b/src/main/java/net/minecraft/server/SpawnerCreature.java
-index 387570ed67..0661ea20d8 100644
+index 387570ed67..97ef41fe82 100644
 --- a/src/main/java/net/minecraft/server/SpawnerCreature.java
 +++ b/src/main/java/net/minecraft/server/SpawnerCreature.java
-@@ -129,7 +129,8 @@ public final class SpawnerCreature {
+@@ -129,9 +129,9 @@ public final class SpawnerCreature {
                              int i2 = blockposition1.getX();
                              int j2 = blockposition1.getY();
                              int k2 = blockposition1.getZ();
 -                            IBlockData iblockdata = worldserver.getType(blockposition1);
 +                            IBlockData iblockdata = worldserver.getTypeIfLoaded(blockposition1);  // Paper - don't load chunks for mob spawn
-+                            if (iblockdata == null) continue; // Paper - don't load chunks for mob spawn
  
-                             if (!iblockdata.isOccluding()) {
+-                            if (!iblockdata.isOccluding()) {
++                            if (iblockdata != null && !iblockdata.isOccluding()) { // Paper - don't load chunks for mob spawn
                                  int l2 = 0;
-@@ -168,6 +169,7 @@ public final class SpawnerCreature {
+                                 int i3 = 0;
+ 
+@@ -167,7 +167,7 @@ public final class SpawnerCreature {
+                                                         i4 = biomebase_biomemeta.c + worldserver.random.nextInt(1 + biomebase_biomemeta.d - biomebase_biomemeta.c);
                                                      }
  
-                                                     if (worldserver.a(enumcreaturetype, biomebase_biomemeta, (BlockPosition) blockposition_mutableblockposition)) {
-+                                                        if (!worldserver.isLoaded(blockposition_mutableblockposition)) continue; // Paper - don't load chunks for mob spawn
+-                                                    if (worldserver.a(enumcreaturetype, biomebase_biomemeta, (BlockPosition) blockposition_mutableblockposition)) {
++                                                    if (worldserver.isLoaded(blockposition_mutableblockposition) && worldserver.a(enumcreaturetype, biomebase_biomemeta, (BlockPosition) blockposition_mutableblockposition)) { // Paper - don't load chunks for mob spawn
                                                          EntityPositionTypes.Surface entitypositiontypes_surface = EntityPositionTypes.a(biomebase_biomemeta.b);
                                                          if (entitypositiontypes_surface != null && a(entitypositiontypes_surface, worldserver, blockposition_mutableblockposition, biomebase_biomemeta.b)) {
                                                              EntityInsentient entityinsentient;
 -- 
-2.18.0
+2.19.0