Procedure Crash with slots

I tried making a chest/box thing so I created the block, and the procedure to open. When I tried it, the game stopped and didn't really crash but crashed.

Crash log thing:

---- Minecraft Crash Report ----
// Ouch. That hurt :(

Time: 6/3/18 8:36 PM
Description: Ticking player

java.lang.ArrayIndexOutOfBoundsException: 35
	at java.util.Arrays$ArrayList.get(Arrays.java:3841)
	at net.minecraft.util.NonNullList.get(NonNullList.java:51)
	at net.minecraft.tileentity.TileEntityLockableLoot.getStackInSlot(TileEntityLockableLoot.java:113)
	at net.minecraft.inventory.Slot.getStack(Slot.java:81)
	at net.minecraft.inventory.Container.detectAndSendChanges(Container.java:97)
	at net.minecraft.entity.player.EntityPlayerMP.onUpdate(EntityPlayerMP.java:365)
	at net.minecraft.world.World.updateEntityWithOptionalForce(World.java:2168)
	at net.minecraft.world.WorldServer.updateEntityWithOptionalForce(WorldServer.java:870)
	at net.minecraft.world.World.updateEntity(World.java:2127)
	at net.minecraft.world.WorldServer.tickPlayers(WorldServer.java:671)
	at net.minecraft.world.World.updateEntities(World.java:1903)
	at net.minecraft.world.WorldServer.updateEntities(WorldServer.java:642)
	at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:840)
	at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:741)
	at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:192)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:590)
	at java.lang.Thread.run(Thread.java:748)


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

-- Head --
Thread: Server thread
Stacktrace:
	at java.util.Arrays$ArrayList.get(Arrays.java:3841)
	at net.minecraft.util.NonNullList.get(NonNullList.java:51)
	at net.minecraft.tileentity.TileEntityLockableLoot.getStackInSlot(TileEntityLockableLoot.java:113)
	at net.minecraft.inventory.Slot.getStack(Slot.java:81)
	at net.minecraft.inventory.Container.detectAndSendChanges(Container.java:97)
	at net.minecraft.entity.player.EntityPlayerMP.onUpdate(EntityPlayerMP.java:365)
	at net.minecraft.world.World.updateEntityWithOptionalForce(World.java:2168)
	at net.minecraft.world.WorldServer.updateEntityWithOptionalForce(WorldServer.java:870)
	at net.minecraft.world.World.updateEntity(World.java:2127)

-- Player being ticked --
Details:
	Entity Type: null (net.minecraft.entity.player.EntityPlayerMP)
	Entity ID: 1173
	Entity Name: Player334
	Entity's Exact location: 263.97, 85.00, 206.34
	Entity's Block location: World: (263,85,206), Chunk: (at 7,5,14 in 16,12; contains blocks 256,0,192 to 271,255,207), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Entity's Momentum: 0.00, -0.08, 0.00
	Entity's Passengers: []
	Entity's Vehicle: ~~ERROR~~ NullPointerException: null
Stacktrace:
	at net.minecraft.world.WorldServer.tickPlayers(WorldServer.java:671)
	at net.minecraft.world.World.updateEntities(World.java:1903)
	at net.minecraft.world.WorldServer.updateEntities(WorldServer.java:642)

-- Affected level --
Details:
	Level name: TW #3
	All players: 1 total; [EntityPlayerMP['Player334'/1173, l='TW #3', x=263.97, y=85.00, z=206.34]]
	Chunk stats: ServerChunkCache: 348 Drop: 0
	Level seed: -2822617044648506876
	Level generator: ID 00 - default, ver 1. Features enabled: true
	Level generator options: 
	Level spawn location: World: (255,64,227), Chunk: (at 15,4,3 in 15,14; contains blocks 240,0,224 to 255,255,239), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 517 game time, 517 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 63352 (now: false), thunder time: 165471 (now: false)
	Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true
Stacktrace:
	at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:840)
	at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:741)
	at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:192)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:590)
	at java.lang.Thread.run(Thread.java:748)

-- System Details --
Details:
	Minecraft Version: 1.12.2
	Operating System: Windows 8.1 (amd64) version 6.3
	Java Version: 1.8.0_152, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 375385840 bytes (357 MB) / 760217600 bytes (725 MB) up to 1415053312 bytes (1349 MB)
	JVM Flags: 0 total; 
	IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
	FML: MCP 9.42 Powered by Forge 14.23.2.2611 5 mods loaded, 5 mods active
	States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored

	| State     | ID                 | Version      | Source                           | Signature |
	|:--------- |:------------------ |:------------ |:-------------------------------- |:--------- |
	| UCHIJAAAA | minecraft          | 1.12.2       | minecraft.jar                    | None      |
	| UCHIJAAAA | mcp                | 9.42         | minecraft.jar                    | None      |
	| UCHIJAAAA | FML                | 8.0.99.99    | forgeSrc-1.12.2-14.23.2.2611.jar | None      |
	| UCHIJAAAA | forge              | 14.23.2.2611 | forgeSrc-1.12.2-14.23.2.2611.jar | None      |
	| UCHIJAAAA | testenvironmentmod | 1.0          | modid-1.0.jar                    | None      |

	Loaded coremods (and transformers): 
	GL info: ~~ERROR~~ RuntimeException: No OpenGL context found in the current thread.
	Profiler Position: N/A (disabled)
	Player Count: 1 / 8; [EntityPlayerMP['Player334'/1173, l='TW #3', x=263.97, y=85.00, z=206.34]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Definitely; Client brand changed to 'fml,forge'

I attached the procedures too.