This error appears when trying to put a freshly spawned in weapon (using /give) into a modification table:

`---- Minecraft Crash Report ----
// Hey, that tickles! Hehehe!

Time: 8/30/16 12:22 PM
Description: Ticking entity

java.lang.NullPointerException: Ticking entity
at net.minecraft.nbt.NBTTagCompound.func_74737_b(NBTTagCompound.java:356)
at net.minecraft.item.ItemStack.func_77946_l(ItemStack.java:413)
at net.minecraft.inventory.Container.func_75142_b(Container.java:143)
at net.minecraft.entity.player.EntityPlayerMP.func_70071_h_(EntityPlayerMP.java:317)
at net.minecraft.world.World.func_72866_a(World.java:2740)
at net.minecraft.world.WorldServer.func_72866_a(WorldServer.java:877)
at net.minecraft.world.World.func_72870_g(World.java:2678)
at net.minecraft.world.World.func_72939_s(World.java:2480)
at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:673)
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:986)
at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:432)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:841)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:693)
at java.lang.Thread.run(Thread.java:745)

A detailed walkthrough of the error, its code path and all known details is as follows:

-- Head --
Stacktrace:
at net.minecraft.nbt.NBTTagCompound.func_74737_b(NBTTagCompound.java:356)
at net.minecraft.item.ItemStack.func_77946_l(ItemStack.java:413)
at net.minecraft.inventory.Container.func_75142_b(Container.java:143)
at net.minecraft.entity.player.EntityPlayerMP.func_70071_h_(EntityPlayerMP.java:317)
at net.minecraft.world.World.func_72866_a(World.java:2740)
at net.minecraft.world.WorldServer.func_72866_a(WorldServer.java:877)
at net.minecraft.world.World.func_72870_g(World.java:2678)

-- Entity being ticked --
Details:
Entity Type: null (net.minecraft.entity.player.EntityPlayerMP)
Entity ID: 58162
Entity Name: NamenGoesRawr
Entity's Exact location: -1103.30, 70.00, -1122.87
Entity's Block location: World: (-1104,70,-1123), Chunk: (at 0,4,13 in -69,-71; contains blocks -1104,0,-1136 to -1089,255,-1121), Region: (-3,-3; contains chunks -96,-96 to -65,-65, blocks -1536,0,-1536 to -1025,255,-1025)
Entity's Momentum: 0.00, -0.08, 0.00
Stacktrace:
at net.minecraft.world.World.func_72939_s(World.java:2480)
at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:673)
`

My guess is that this issue occurs when the weapon ammo NBT Tag is null (Meaning its been spawned in without having its proper attributes)