Invalid item entities without actual items exist.

Ever since 1.9 up to the 1.9.1 pre-releases, when there is a lot of item entities, the item itself may despawn, but the item entity still exists causing the item entity to be invalid.
This happening causes this on the Game Output:

[Client thread/ERROR]: Item entity 656313 has no item?!
[Client thread/ERROR]: Item entity 656313 has no item?!
[Client thread/ERROR]: Item entity 656313 has no item?!
[Client thread/ERROR]: Item entity 656313 has no item?!
[Client thread/ERROR]: Item entity 656313 has no item?!
[Client thread/ERROR]: Item entity 656313 has no item?!
[Client thread/ERROR]: Item entity 656313 has no item?!
[Client thread/ERROR]: Item entity 656313 has no item?!
[Client thread/ERROR]: Item entity 656313 has no item?!
[Client thread/ERROR]: Item entity 656313 has no item?!

Here is the Game Output:

[17:27:19] [Client thread/ERROR]: Can't ping 198.24.163.58:25565: Internal Exception: io.netty.handler.codec.DecoderException: com.google.gson.JsonSyntaxException: Expected status to be a JsonObject, was "Ser...g."
[17:28:05] [Client thread/INFO]: Connecting to 198.24.167.211, 25565
[17:28:06] [Client thread/INFO]: [CHAT] Foltrox joined the game
[17:28:08] [Client thread/INFO]: [CHAT] Welcome [Hub]Foltrox to the server!
[17:28:18] [Client thread/INFO]: [CHAT] You do not have access to that command.
[17:28:23] [Client thread/INFO]: [CHAT] You do not have access to that command.
[17:29:06] [Client thread/INFO]: [CHAT] Foltrox has just earned the achievement [Taking Inventory]
[17:32:50] [Server thread/INFO]: Starting integrated minecraft server version 1.9
[17:32:50] [Server thread/INFO]: Generating keypair
[17:32:50] [Server thread/INFO]: Converting map!
[17:32:50] [Server thread/INFO]: Scanning folders...
[17:32:50] [Server thread/INFO]: Total conversion count is 0
[17:32:51] [Server thread/INFO]: Preparing start region for level 0
[17:32:52] [Server thread/INFO]: Preparing spawn area: 6%
[17:32:53] [Server thread/INFO]: Preparing spawn area: 10%
[17:32:54] [Server thread/INFO]: Preparing spawn area: 13%
[17:32:55] [Server thread/INFO]: Preparing spawn area: 17%
[17:32:56] [Server thread/INFO]: Preparing spawn area: 21%
[17:32:57] [Server thread/INFO]: Preparing spawn area: 25%
[17:32:58] [Server thread/INFO]: Preparing spawn area: 29%
[17:32:59] [Server thread/INFO]: Preparing spawn area: 33%
[17:33:00] [Server thread/INFO]: Preparing spawn area: 37%
[17:33:01] [Server thread/INFO]: Preparing spawn area: 41%
[17:33:02] [Server thread/INFO]: Preparing spawn area: 45%
[17:33:03] [Server thread/INFO]: Preparing spawn area: 49%
[17:33:04] [Server thread/INFO]: Preparing spawn area: 53%
[17:33:05] [Server thread/INFO]: Preparing spawn area: 57%
[17:33:06] [Server thread/INFO]: Preparing spawn area: 60%
[17:33:07] [Server thread/INFO]: Preparing spawn area: 64%
[17:33:08] [Server thread/INFO]: Preparing spawn area: 68%
[17:33:09] [Server thread/INFO]: Preparing spawn area: 72%
[17:33:10] [Server thread/INFO]: Preparing spawn area: 76%
[17:33:11] [Server thread/INFO]: Preparing spawn area: 79%
[17:33:12] [Server thread/INFO]: Preparing spawn area: 83%
[17:33:13] [Server thread/INFO]: Preparing spawn area: 87%
[17:33:14] [Server thread/INFO]: Preparing spawn area: 91%
[17:33:15] [Server thread/INFO]: Preparing spawn area: 95%
[17:33:16] [Server thread/INFO]: Preparing spawn area: 98%
[17:33:17] [Server thread/INFO]: Changing view distance to 4, from 10
[17:33:17] [Server thread/INFO]: Foltrox[local:E:18cc410b] logged in with entity id 80158 at (159.5, 63.0, 233.5)
[17:33:17] [Server thread/INFO]: Foltrox joined the game
[17:33:21] [Server thread/INFO]: [Foltrox: Set own game mode to Creative Mode]
[17:33:21] [Client thread/INFO]: [CHAT] Your game mode has been updated
[17:33:38] [Server thread/INFO]: [Foltrox: Game rule has been updated]
[17:33:38] [Client thread/INFO]: [CHAT] Game rule has been updated
[17:33:39] [Server thread/INFO]: Foltrox has just earned the achievement [Taking Inventory]
[17:33:39] [Client thread/INFO]: [CHAT] Foltrox has just earned the achievement [Taking Inventory]
[17:37:28] [Server thread/INFO]: Saving and pausing game...
[17:37:28] [Server thread/INFO]: Saving chunks for level 'Griefer'/Overworld
[17:37:28] [Server thread/INFO]: Saving chunks for level 'Griefer'/Nether
[17:37:28] [Server thread/INFO]: Saving chunks for level 'Griefer'/The End
[17:38:29] [Server thread/INFO]: Saving and pausing game...
[17:38:29] [Server thread/INFO]: Saving chunks for level 'Griefer'/Overworld
[17:38:29] [Server thread/INFO]: Saving chunks for level 'Griefer'/Nether
[17:38:29] [Server thread/INFO]: Saving chunks for level 'Griefer'/The End
[17:41:21] [Server thread/INFO]: Saving and pausing game...
[17:41:21] [Server thread/INFO]: Saving chunks for level 'Griefer'/Overworld
[17:41:21] [Server thread/INFO]: Saving chunks for level 'Griefer'/Nether
[17:41:21] [Server thread/INFO]: Saving chunks for level 'Griefer'/The End
[17:41:47] [Server thread/INFO]: Saving and pausing game...
[17:41:47] [Server thread/INFO]: Saving chunks for level 'Griefer'/Overworld
[17:41:47] [Server thread/INFO]: Saving chunks for level 'Griefer'/Nether
[17:41:47] [Server thread/INFO]: Saving chunks for level 'Griefer'/The End
[17:42:31] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 2883ms behind, skipping 57 tick(s)
[17:42:39] [Client thread/ERROR]: Item entity 656313 has no item?!
[17:42:39] [Client thread/ERROR]: Item entity 656313 has no item?!
[17:42:39] [Client thread/ERROR]: Item entity 656313 has no item?!
[17:42:40] [Client thread/ERROR]: Item entity 656313 has no item?!
[17:42:40] [Client thread/ERROR]: Item entity 656313 has no item?!
[17:42:40] [Client thread/ERROR]: Item entity 656313 has no item?!
[17:42:41] [Client thread/ERROR]: Item entity 656313 has no item?!
[17:42:41] [Client thread/ERROR]: Item entity 656313 has no item?!
[17:42:41] [Client thread/ERROR]: Item entity 656313 has no item?!
[17:42:41] [Client thread/ERROR]: Item entity 656313 has no item?!
[17:43:43] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 36193ms behind, skipping 723 tick(s)
[17:45:07] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 2221ms behind, skipping 44 tick(s)
[17:45:23] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 3058ms behind, skipping 61 tick(s)
[17:45:44] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 8418ms behind, skipping 168 tick(s)
[17:45:58] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 3882ms behind, skipping 77 tick(s)
[17:46:13] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 4281ms behind, skipping 85 tick(s)
[17:46:30] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 3852ms behind, skipping 77 tick(s)
[17:46:50] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 5481ms behind, skipping 109 tick(s)
[17:47:04] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 2871ms behind, skipping 57 tick(s)
[17:48:26] [Client thread/ERROR]: Item entity 4021950 has no item?!
[17:48:26] [Client thread/ERROR]: Item entity 4021950 has no item?!
[17:48:26] [Client thread/ERROR]: Item entity 4021950 has no item?!
[17:53:46] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 3068ms behind, skipping 61 tick(s)
[17:54:32] [Server thread/WARN]: Can't keep up! Did the system time change, or is the server overloaded? Running 2986ms behind, skipping 59 tick(s)
[17:57:46] [Server thread/INFO]: Saving and pausing game...
[17:57:46] [Server thread/INFO]: Saving chunks for level 'Griefer'/Overworld
[17:57:46] [Server thread/INFO]: Saving chunks for level 'Griefer'/Nether
[17:57:46] [Server thread/INFO]: Saving chunks for level 'Griefer'/The End
[17:57:47] [Server thread/INFO]: Stopping server
[17:57:47] [Server thread/INFO]: Saving players
[17:57:47] [Server thread/INFO]: Saving worlds
[17:57:47] [Server thread/INFO]: Saving chunks for level 'Griefer'/Overworld
[17:57:47] [Server thread/INFO]: Saving chunks for level 'Griefer'/Nether
[17:57:47] [Server thread/INFO]: Saving chunks for level 'Griefer'/The End
[17:57:49] [Client thread/INFO]: Stopping!
[17:57:49] [Client thread/INFO]: SoundSystem shutting down...
[17:57:49] [Client thread/WARN]: Author: Paul Lamb, www.paulscode.com
Java HotSpot(TM) Client VM warning: Using incremental CMS is deprecated and will likely be removed in a future release

To Reproduce:
1. Create a world.
2. Make lots of item entities. I usually do that by blowing up my world with TNT and Redstone Blocks.
3. See your Game Output for any invalid item entities.