---- Minecraft Crash Report ----
// Who set us up the TNT?

Time: 16/08/20 00:01
Description: Rendering screen

java.lang.ArrayIndexOutOfBoundsException: null

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

-- Head --
Thread: Render thread
Stacktrace:
at net.minecraft.client.renderer.GameRenderer.func_195458_a(GameRenderer.java:494)

-- Screen render details --
Details:
Screen name: com.supermartijn642.simplemagnets.gui.MagnetContainerScreen
Mouse location: Scaled: (341, 192). Absolute: (683.000000, 384.000000)
Screen size: Scaled: (683, 384). Absolute: (1366, 768). Scale factor of 2.000000
Stacktrace:
at net.minecraft.client.renderer.GameRenderer.func_195458_a(GameRenderer.java:494)
at net.minecraft.client.Minecraft.func_195542_b(Minecraft.java:954)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:585)
at net.minecraft.client.main.Main.main(Main.java:184)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at net.minecraftforge.fml.loading.FMLClientLaunchProvider.lambda$launchService$0(FMLClientLaunchProvider.java:51)
at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37)
at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:54)
at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:72)
at cpw.mods.modlauncher.Launcher.run(Launcher.java:81)
at cpw.mods.modlauncher.Launcher.main(Launcher.java:65)

-- Affected level --
Details:
All players: 1 total; [ClientPlayerEntity['Rodrigonmiers'/142, l='ClientLevel', x=-1842.70, y=63.00, z=510.35]]
Chunk stats: Client Chunk Cache: 841, 575
Level dimension: minecraft:overworld
Level spawn location: World: (-192,64,16), Chunk: (at 0,4,0 in -12,1; contains blocks -192,0,16 to -177,255,31), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
Level time: 11223774 game time, 12921076 day time
Server brand: forge
Server type: Integrated singleplayer server

-- System Details --
Details:
Minecraft Version: 1.16.2
Minecraft Version ID: 1.16.2
Operating System: Windows 10 (amd64) version 10.0
Java Version: 1.8.0_261, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 360579176 bytes (343 MB) / 984989696 bytes (939 MB) up to 4231266304 bytes (4035 MB)
CPUs: 4
JVM Flags: 6 total; -Xmn128M -Xmx4047M -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -XX:+UseConcMarkSweepGC -XX:MaxPermSize=1000M
ModLauncher: 6.1.1+74+master.966c698
ModLauncher launch target: fmlclient
ModLauncher naming: srg
ModLauncher services:
/mixin-0.8.jar mixin PLUGINSERVICE
/eventbus-3.0.3-service.jar eventbus PLUGINSERVICE
/forge-1.16.2-33.0.2.jar object_holder_definalize PLUGINSERVICE
/forge-1.16.2-33.0.2.jar runtime_enum_extender PLUGINSERVICE
/accesstransformers-2.2.0-shadowed.jar accesstransformer PLUGINSERVICE
/forge-1.16.2-33.0.2.jar capability_inject_definalize PLUGINSERVICE
/forge-1.16.2-33.0.2.jar runtimedistcleaner PLUGINSERVICE
/mixin-0.8.jar mixin TRANSFORMATIONSERVICE
/forge-1.16.2-33.0.2.jar fml TRANSFORMATIONSERVICE
FML: 33.0
Forge: net.minecraftforge:33.0.2
FML Language Providers:
[email protected]
minecraft@1
Mod List:
forge-1.16.2-33.0.2-client.jar Minecraft {[email protected] DONE}
doubledoors_1.16.2-2.1.jar Double Doors {[email protected] DONE}
forge-curioofundying-1.16.2-5.0.0.0.jar Curio of Undying {[email protected] DONE}
bspawncontrol_1.16.2-1.1.jar Better Spawner Control {[email protected] DONE}
Compressium-1.0.27.jar Compressium {[email protected] DONE}
expandedstorage-3.0.0+1.16.2.jar Expanded Storage {[email protected] DONE}
TrashSlot_1.16.2-12.1.0.jar TrashSlot {[email protected] DONE}
simplemagnets-1.0.4a-mc1.16.jar Simple Magnets {[email protected] DONE}
curiouselytra-forge-1.16.2-4.0.0.0.jar Curious Elytra {[email protected] DONE}
shulkerbox-1.16.2-1.0.1.jar Advanced Shulkerboxes {[email protected] DONE}
jei-1.16.2-7.1.0.11.jar Just Enough Items {[email protected] DONE}
easyelytrato_1.16.2-1.4.jar Easy Elytra Takeoff {[email protected] DONE}
FallingTree-Forge-1.16.2-2.2.1.jar Falling Tree {[email protected] DONE}
simplybackpacks-1.16.2-1.4.10.jar Simply Backpacks {[email protected] DONE}
caelus-forge-1.16.2-2.0.0.0.jar Caelus API {[email protected] DONE}
forge-1.16.2-33.0.2-universal.jar Forge {[email protected] DONE}
jeiintegration_1.16.2-5.0.0.6.jar JEI Integration {[email protected] DONE}
infinitetrading_1.16.2-1.1.jar Infinite Trading {[email protected] DONE}
CraftingCraft_1.16.2-9.1.0.jar CraftingCraft {[email protected] DONE}
reap-1.16.2-1.0.1.jar Reap Mod {[email protected] DONE}
invtweaks-1.16.2-1.0.0.jar Inventory Tweaks Renewed {[email protected] DONE}
curios-forge-1.16.2-4.0.0.0.jar Curios API {[email protected] DONE}
gravestone-1.16.1-1.0.1.jar Gravestone Mod {[email protected] DONE}
collective-1.16.2-1.37.jar Collective {[email protected] DONE}
CraftingTweaks_1.16.2-12.1.0.jar Crafting Tweaks {[email protected] DONE}
Launched Version: 1.16.2-forge-33.0.2
Backend library: LWJGL version 3.2.2 build 10
Backend API: GeForce 210/PCIe/SSE2 GL version 3.3.0, NVIDIA Corporation
GL Caps: Using framebuffer using OpenGL 3.0
Using VBOs: Yes
Is Modded: Definitely; Client brand changed to 'forge'
Type: Client (map_client.txt)
Graphics mode: fast
Resource Packs: vanilla (incompatible), mod_resources (incompatible)
Current Language: Español (España)
CPU: 4x Intel(R) Core(TM) i3-3220 CPU @ 3.30GHz

I fixed it now in version 1.0.5.

Thanks for the report!