Note: I could not find the category to place Server Bugs, so I placed it here
Issue: Server Stack Trace error when Shulker shoots Bullet
How to reproduce: Run a Server and make a Shulker shoot at you.
Logs:

[12:51:21] [Server thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NullPointerException
at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:46) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.D(SourceFile:592) [minecraft_server.15w32c.jar:?]
at kp.D(SourceFile:298) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.C(SourceFile:548) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:452) [minecraft_server.15w32c.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_45]
Caused by: java.lang.NullPointerException
at acx.a(SourceFile:124) ~[minecraft_server.15w32c.jar:?]
at abw.a(SourceFile:144) ~[minecraft_server.15w32c.jar:?]
at li.a(SourceFile:250) ~[minecraft_server.15w32c.jar:?]
at lo.a(SourceFile:513) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:32) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:9) ~[minecraft_server.15w32c.jar:?]
at fh$1.run(SourceFile:13) ~[minecraft_server.15w32c.jar:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:45) ~[minecraft_server.15w32c.jar:?]
... 5 more
[12:51:26] [Server thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NullPointerException
at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:46) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.D(SourceFile:592) [minecraft_server.15w32c.jar:?]
at kp.D(SourceFile:298) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.C(SourceFile:548) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:452) [minecraft_server.15w32c.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_45]
Caused by: java.lang.NullPointerException
at acx.a(SourceFile:124) ~[minecraft_server.15w32c.jar:?]
at abw.a(SourceFile:144) ~[minecraft_server.15w32c.jar:?]
at li.a(SourceFile:250) ~[minecraft_server.15w32c.jar:?]
at lo.a(SourceFile:513) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:32) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:9) ~[minecraft_server.15w32c.jar:?]
at fh$1.run(SourceFile:13) ~[minecraft_server.15w32c.jar:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:45) ~[minecraft_server.15w32c.jar:?]
... 5 more
[12:51:26] [Server thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NullPointerException
at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:46) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.D(SourceFile:592) [minecraft_server.15w32c.jar:?]
at kp.D(SourceFile:298) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.C(SourceFile:548) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:452) [minecraft_server.15w32c.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_45]
Caused by: java.lang.NullPointerException
at acx.a(SourceFile:124) ~[minecraft_server.15w32c.jar:?]
at abw.a(SourceFile:144) ~[minecraft_server.15w32c.jar:?]
at li.a(SourceFile:250) ~[minecraft_server.15w32c.jar:?]
at lo.a(SourceFile:513) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:32) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:9) ~[minecraft_server.15w32c.jar:?]
at fh$1.run(SourceFile:13) ~[minecraft_server.15w32c.jar:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:45) ~[minecraft_server.15w32c.jar:?]
... 5 more
[12:51:26] [Server thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NullPointerException
at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:46) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.D(SourceFile:592) [minecraft_server.15w32c.jar:?]
at kp.D(SourceFile:298) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.C(SourceFile:548) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:452) [minecraft_server.15w32c.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_45]
Caused by: java.lang.NullPointerException
at acx.a(SourceFile:124) ~[minecraft_server.15w32c.jar:?]
at abw.a(SourceFile:144) ~[minecraft_server.15w32c.jar:?]
at li.a(SourceFile:250) ~[minecraft_server.15w32c.jar:?]
at lo.a(SourceFile:513) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:32) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:9) ~[minecraft_server.15w32c.jar:?]
at fh$1.run(SourceFile:13) ~[minecraft_server.15w32c.jar:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:45) ~[minecraft_server.15w32c.jar:?]
... 5 more
[12:51:31] [Server thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NullPointerException
at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:46) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.D(SourceFile:592) [minecraft_server.15w32c.jar:?]
at kp.D(SourceFile:298) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.C(SourceFile:548) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:452) [minecraft_server.15w32c.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_45]
Caused by: java.lang.NullPointerException
at acx.a(SourceFile:124) ~[minecraft_server.15w32c.jar:?]
at abw.a(SourceFile:144) ~[minecraft_server.15w32c.jar:?]
at li.a(SourceFile:250) ~[minecraft_server.15w32c.jar:?]
at lo.a(SourceFile:513) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:32) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:9) ~[minecraft_server.15w32c.jar:?]
at fh$1.run(SourceFile:13) ~[minecraft_server.15w32c.jar:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:45) ~[minecraft_server.15w32c.jar:?]
... 5 more
[12:51:31] [Server thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NullPointerException
at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:46) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.D(SourceFile:592) [minecraft_server.15w32c.jar:?]
at kp.D(SourceFile:298) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.C(SourceFile:548) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:452) [minecraft_server.15w32c.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_45]
Caused by: java.lang.NullPointerException
at acx.a(SourceFile:124) ~[minecraft_server.15w32c.jar:?]
at abw.a(SourceFile:144) ~[minecraft_server.15w32c.jar:?]
at li.a(SourceFile:250) ~[minecraft_server.15w32c.jar:?]
at lo.a(SourceFile:513) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:32) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:9) ~[minecraft_server.15w32c.jar:?]
at fh$1.run(SourceFile:13) ~[minecraft_server.15w32c.jar:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:45) ~[minecraft_server.15w32c.jar:?]
... 5 more
[12:51:31] [Server thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NullPointerException
at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:46) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.D(SourceFile:592) [minecraft_server.15w32c.jar:?]
at kp.D(SourceFile:298) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.C(SourceFile:548) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:452) [minecraft_server.15w32c.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_45]
Caused by: java.lang.NullPointerException
at acx.a(SourceFile:124) ~[minecraft_server.15w32c.jar:?]
at abw.a(SourceFile:144) ~[minecraft_server.15w32c.jar:?]
at li.a(SourceFile:250) ~[minecraft_server.15w32c.jar:?]
at lo.a(SourceFile:513) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:32) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:9) ~[minecraft_server.15w32c.jar:?]
at fh$1.run(SourceFile:13) ~[minecraft_server.15w32c.jar:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:45) ~[minecraft_server.15w32c.jar:?]
... 5 more
[12:51:32] [Server thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NullPointerException
at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:46) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.D(SourceFile:592) [minecraft_server.15w32c.jar:?]
at kp.D(SourceFile:298) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.C(SourceFile:548) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:452) [minecraft_server.15w32c.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_45]
Caused by: java.lang.NullPointerException
at acx.a(SourceFile:124) ~[minecraft_server.15w32c.jar:?]
at abw.a(SourceFile:144) ~[minecraft_server.15w32c.jar:?]
at li.a(SourceFile:250) ~[minecraft_server.15w32c.jar:?]
at lo.a(SourceFile:513) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:32) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:9) ~[minecraft_server.15w32c.jar:?]
at fh$1.run(SourceFile:13) ~[minecraft_server.15w32c.jar:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:45) ~[minecraft_server.15w32c.jar:?]
... 5 more
[12:51:32] [Server thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NullPointerException
at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:46) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.D(SourceFile:592) [minecraft_server.15w32c.jar:?]
at kp.D(SourceFile:298) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.C(SourceFile:548) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:452) [minecraft_server.15w32c.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_45]
Caused by: java.lang.NullPointerException
at acx.a(SourceFile:124) ~[minecraft_server.15w32c.jar:?]
at abw.a(SourceFile:144) ~[minecraft_server.15w32c.jar:?]
at li.a(SourceFile:250) ~[minecraft_server.15w32c.jar:?]
at lo.a(SourceFile:513) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:32) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:9) ~[minecraft_server.15w32c.jar:?]
at fh$1.run(SourceFile:13) ~[minecraft_server.15w32c.jar:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:45) ~[minecraft_server.15w32c.jar:?]
... 5 more
[12:51:32] [Server thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NullPointerException
at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:46) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.D(SourceFile:592) [minecraft_server.15w32c.jar:?]
at kp.D(SourceFile:298) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.C(SourceFile:548) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:452) [minecraft_server.15w32c.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_45]
Caused by: java.lang.NullPointerException
at acx.a(SourceFile:124) ~[minecraft_server.15w32c.jar:?]
at abw.a(SourceFile:144) ~[minecraft_server.15w32c.jar:?]
at li.a(SourceFile:250) ~[minecraft_server.15w32c.jar:?]
at lo.a(SourceFile:513) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:32) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:9) ~[minecraft_server.15w32c.jar:?]
at fh$1.run(SourceFile:13) ~[minecraft_server.15w32c.jar:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:45) ~[minecraft_server.15w32c.jar:?]
... 5 more
[12:51:32] [Server thread/FATAL]: Error executing task
java.util.concurrent.ExecutionException: java.lang.NullPointerException
at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:46) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.D(SourceFile:592) [minecraft_server.15w32c.jar:?]
at kp.D(SourceFile:298) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.C(SourceFile:548) [minecraft_server.15w32c.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:452) [minecraft_server.15w32c.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_45]
Caused by: java.lang.NullPointerException
at acx.a(SourceFile:124) ~[minecraft_server.15w32c.jar:?]
at abw.a(SourceFile:144) ~[minecraft_server.15w32c.jar:?]
at li.a(SourceFile:250) ~[minecraft_server.15w32c.jar:?]
at lo.a(SourceFile:513) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:32) ~[minecraft_server.15w32c.jar:?]
at jb.a(SourceFile:9) ~[minecraft_server.15w32c.jar:?]
at fh$1.run(SourceFile:13) ~[minecraft_server.15w32c.jar:?]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_45]
at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_45]
at g.a(SourceFile:45) ~[minecraft_server.15w32c.jar:?]
... 5 more