Paper/patches/server/0447-Avoid-error-bubbling-up-when-item-stack-is-empty-in-.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Toon Schoenmakers <nighteyes1993@gmail.com>
Date: Fri, 23 Oct 2020 15:01:44 +0200
Subject: [PATCH] Avoid error bubbling up when item stack is empty in fishing
 loot

This can realistically only happen if there's custom loot active on fishing
which can return 0 items. This would disconnect the player who's fishing.

diff --git a/src/main/java/net/minecraft/world/entity/projectile/FishingHook.java b/src/main/java/net/minecraft/world/entity/projectile/FishingHook.java
index 94bdd467108bc5fd0211f67a792787ef7c356619..b6ebae97dc863ba1748e9b32555f940077846be8 100644
--- a/src/main/java/net/minecraft/world/entity/projectile/FishingHook.java
+++ b/src/main/java/net/minecraft/world/entity/projectile/FishingHook.java
@@ -503,9 +503,15 @@ public class FishingHook extends Projectile {
 
                 while (iterator.hasNext()) {
                     ItemStack itemstack1 = (ItemStack) iterator.next();
-                    ItemEntity entityitem = new ItemEntity(this.level(), this.getX(), this.getY(), this.getZ(), itemstack1);
+                    // Paper start - new ItemEntity would throw if for whatever reason (mostly shitty datapacks) the itemstack1 turns out to be empty
+                    // if the item stack is empty we instead just have our entityitem as null
+                    ItemEntity entityitem = null;
+                    if (!itemstack1.isEmpty()) {
+                        entityitem = new ItemEntity(this.level(), this.getX(), this.getY(), this.getZ(), itemstack1);
+                    }
+                    // Paper end
                     // CraftBukkit start
-                    PlayerFishEvent playerFishEvent = new PlayerFishEvent((Player) entityhuman.getBukkitEntity(), entityitem.getBukkitEntity(), (FishHook) this.getBukkitEntity(), PlayerFishEvent.State.CAUGHT_FISH);
+                    PlayerFishEvent playerFishEvent = new PlayerFishEvent((Player) entityhuman.getBukkitEntity(), entityitem != null ? entityitem.getBukkitEntity() : null, (FishHook) this.getBukkitEntity(), PlayerFishEvent.State.CAUGHT_FISH); // Paper - entityitem may be null
                     playerFishEvent.setExpToDrop(this.random.nextInt(6) + 1);
                     this.level().getCraftServer().getPluginManager().callEvent(playerFishEvent);
 
@@ -518,8 +524,12 @@ public class FishingHook extends Projectile {
                     double d2 = entityhuman.getZ() - this.getZ();
                     double d3 = 0.1D;
 
-                    entityitem.setDeltaMovement(d0 * 0.1D, d1 * 0.1D + Math.sqrt(Math.sqrt(d0 * d0 + d1 * d1 + d2 * d2)) * 0.08D, d2 * 0.1D);
-                    this.level().addFreshEntity(entityitem);
+                    // Paper start - entity item can be null, so we need to check against this
+                    if (entityitem != null) {
+                        entityitem.setDeltaMovement(d0 * 0.1D, d1 * 0.1D + Math.sqrt(Math.sqrt(d0 * d0 + d1 * d1 + d2 * d2)) * 0.08D, d2 * 0.1D);
+                        this.level().addFreshEntity(entityitem);
+                    }
+                    // Paper end
                     // CraftBukkit start - this.random.nextInt(6) + 1 -> playerFishEvent.getExpToDrop()
                     if (playerFishEvent.getExpToDrop() > 0) {
                         entityhuman.level().addFreshEntity(new ExperienceOrb(entityhuman.level(), entityhuman.getX(), entityhuman.getY() + 0.5D, entityhuman.getZ() + 0.5D, playerFishEvent.getExpToDrop(), org.bukkit.entity.ExperienceOrb.SpawnReason.FISHING, this.getPlayerOwner(), this)); // Paper