Fix NPE in clipsAnything at world height

If the block is out of bounds, then the block state may
be null.

patches/server/0029-Actually-optimise-explosions.patch

@@ -34,7 +34,7 @@ The results indicate that this logic is 5 times faster than Vanilla
 and 2.3 times faster than Lithium.
 
 diff --git a/src/main/java/net/minecraft/world/level/Explosion.java b/src/main/java/net/minecraft/world/level/Explosion.java
-index e8c4815960ab144298d4352f393b9670e7004e62..905602f0535ba899057a8bdfe165670944daa271 100644
+index e8c4815960ab144298d4352f393b9670e7004e62..744b9e4666aade8d84f84807900d4ee31afef7b6 100644
 --- a/src/main/java/net/minecraft/world/level/Explosion.java
 +++ b/src/main/java/net/minecraft/world/level/Explosion.java
 @@ -96,6 +96,271 @@ public class Explosion {
@@ -209,7 +209,7 @@ index e8c4815960ab144298d4352f393b9670e7004e62..905602f0535ba899057a8bdfe1656709
 +            }
 +
 +            final BlockState blockState = cachedBlock.blockState;
-+            if (!blockState.emptyCollisionShape()) {
++            if (blockState != null && !blockState.emptyCollisionShape()) {
 +                net.minecraft.world.phys.shapes.VoxelShape collision = cachedBlock.cachedCollisionShape;
 +                if (collision == null) {
 +                    collision = blockState.getConstantCollisionShape();