Futurepack version 21.0.4
When you place EPU in the world and break it the game crashes.
---- Minecraft Crash Report ----
// Hey, that tickles! Hehehe!

Time: 10.1.21. 09.50
Description: Ticking player

java.lang.NullPointerException: Ticking player
at futurepack.common.item.misc.ItemAncientEnergy.absorbEnergy(ItemAncientEnergy.java:87) ~[?:1.16.4-21.0.4] {re:classloading}
at futurepack.common.item.misc.ItemAncientEnergy.func_77663_a(ItemAncientEnergy.java:41) ~[?:1.16.4-21.0.4] {re:classloading}
at net.minecraft.item.ItemStack.func_77945_a(ItemStack.java:431) ~[?:?] {re:classloading}
at net.minecraft.entity.player.PlayerInventory.func_70429_k(PlayerInventory.java:238) ~[?:?] {re:classloading}
at net.minecraft.entity.player.PlayerEntity.func_70636_d(PlayerEntity.java:487) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.entity.LivingEntity.func_70071_h_(LivingEntity.java:2158) ~[?:?] {re:classloading}
at net.minecraft.entity.player.PlayerEntity.func_70071_h_(PlayerEntity.java:223) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.entity.player.ServerPlayerEntity.func_71127_g(ServerPlayerEntity.java:404) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.network.play.ServerPlayNetHandler.func_73660_a(ServerPlayNetHandler.java:207) ~[?:?] {re:classloading}
at net.minecraft.network.NetworkManager.func_74428_b(NetworkManager.java:226) ~[?:?] {re:classloading}
at net.minecraft.network.NetworkSystem.func_151269_c(NetworkSystem.java:134) ~[?:?] {re:classloading}
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:864) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:786) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:78) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
at net.minecraft.server.MinecraftServer.func_240802_v_(MinecraftServer.java:641) [?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.server.MinecraftServer.lambda$startServer$0(MinecraftServer.java:232) [?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.server.MinecraftServer$$Lambda$6148/1149582388.run(Unknown Source) [?:?] {}
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_51] {}

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

-- Head --
Thread: Server thread
Stacktrace:
at futurepack.common.item.misc.ItemAncientEnergy.absorbEnergy(ItemAncientEnergy.java:87) ~[?:1.16.4-21.0.4] {re:classloading}
at futurepack.common.item.misc.ItemAncientEnergy.func_77663_a(ItemAncientEnergy.java:41) ~[?:1.16.4-21.0.4] {re:classloading}
at net.minecraft.item.ItemStack.func_77945_a(ItemStack.java:431) ~[?:?] {re:classloading}
at net.minecraft.entity.player.PlayerInventory.func_70429_k(PlayerInventory.java:238) ~[?:?] {re:classloading}
at net.minecraft.entity.player.PlayerEntity.func_70636_d(PlayerEntity.java:487) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.entity.LivingEntity.func_70071_h_(LivingEntity.java:2158) ~[?:?] {re:classloading}
at net.minecraft.entity.player.PlayerEntity.func_70071_h_(PlayerEntity.java:223) ~[?:?] {re:classloading,pl:accesstransformer:B}
-- Player being ticked --
Details:
Entity Type: minecraft:player (net.minecraft.entity.player.ServerPlayerEntity)
Entity ID: 1409
Entity Name: Ajzaklija
Entity's Exact location: -143.96, 69.00, 201.34
Entity's Block location: World: (-144,69,201), Chunk: (at 0,4,9 in -9,12; contains blocks -144,0,192 to -129,255,207), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
Entity's Momentum: 0.00, -0.08, 0.00
Entity's Passengers: []
Entity's Vehicle: ERROR NullPointerException: null
Stacktrace:
at net.minecraft.entity.player.ServerPlayerEntity.func_71127_g(ServerPlayerEntity.java:404) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.network.play.ServerPlayNetHandler.func_73660_a(ServerPlayNetHandler.java:207) ~[?:?] {re:classloading}
at net.minecraft.network.NetworkManager.func_74428_b(NetworkManager.java:226) ~[?:?] {re:classloading}
at net.minecraft.network.NetworkSystem.func_151269_c(NetworkSystem.java:134) ~[?:?] {re:classloading}
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:864) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:786) ~[?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:78) ~[?:?] {re:classloading,pl:runtimedistcleaner:A}
at net.minecraft.server.MinecraftServer.func_240802_v_(MinecraftServer.java:641) [?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.server.MinecraftServer.lambda$startServer$0(MinecraftServer.java:232) [?:?] {re:classloading,pl:accesstransformer:B}
at net.minecraft.server.MinecraftServer$$Lambda$6148/1149582388.run(Unknown Source) [?:?] {}
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_51] {}

-- System Details --
Details:
Minecraft Version: 1.16.4
Minecraft Version ID: 1.16.4
Operating System: Windows 10 (amd64) version 10.0
Java Version: 1.8.0_51, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 1099225912 bytes (1048 MB) / 2147483648 bytes (2048 MB) up to 2147483648 bytes (2048 MB)
CPUs: 4
JVM Flags: 9 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
ModLauncher: 8.0.6+85+master.325de55
ModLauncher launch target: fmlclient
ModLauncher naming: srg
ModLauncher services:
/mixin-0.8.2.jar mixin PLUGINSERVICE
/eventbus-3.0.5-service.jar eventbus PLUGINSERVICE
/forge-1.16.4-35.1.4.jar object_holder_definalize PLUGINSERVICE
/forge-1.16.4-35.1.4.jar runtime_enum_extender PLUGINSERVICE
/accesstransformers-2.2.0-shadowed.jar accesstransformer PLUGINSERVICE
/forge-1.16.4-35.1.4.jar capability_inject_definalize PLUGINSERVICE
/forge-1.16.4-35.1.4.jar runtimedistcleaner PLUGINSERVICE
/mixin-0.8.2.jar mixin TRANSFORMATIONSERVICE
/forge-1.16.4-35.1.4.jar fml TRANSFORMATIONSERVICE
FML: 35.1
Forge: net.minecraftforge:35.1.4
FML Language Providers:
[email protected]
minecraft@1
Mod List:
forge-1.16.4-35.1.4-client.jar |Minecraft |minecraft |1.16.4 |DONE |NOSIGNATURE
DungeonCrawl-1.16.3-2.2.2.jar |Dungeon Crawl |dungeoncrawl |2.2.2 |DONE |NOSIGNATURE
MutantBeasts-1.16.4-1.1.3.jar |Mutant Beasts |mutantbeasts |1.16.4-1.1.3 |DONE |d9:be:bd:b6:9a:e4:14:aa:05:67:fb:84:06:77:a0:c5:10:ec:27:15:1b:d6:c0:88:49:9a:ef:26:77:61:0b:5e
forge-1.16.4-35.1.4-universal.jar |Forge |forge |35.1.4 |DONE |22:af:21:d8:19:82:7f:93:94:fe:2b:ac:b7:e4:41:57:68:39:87:b1:a7:5c:c6:44:f9:25:74:21:14:f5:0d:90
looot-1.16.4-1.0.0.3.jar |Looot |looot |1.0.0.3 |DONE |NOSIGNATURE
FastLeafDecay-v25.jar |FastLeafDecay |fastleafdecay |v25 |DONE |NOSIGNATURE
BetterMineshafts-Forge-1.16.3-1.1.1.jar |YUNG's Better Mineshafts |bettermineshafts |1.16.3-1.1.1 |DONE |NOSIGNATURE
workshopsofdoom-1.16.4-1.1.0.0.jar |Workshops of Doom |workshopsofdoom |1.1.0.0 |DONE |NOSIGNATURE
Futurepack-1.16.4-21.0.4.jar |Futurepack |futurepack |21.0.4 |DONE |78:ee:c7:a4:2b:54:18:c6:71:6a:84:82:fa:d9:98:5a:a8:33:83:96:b1:4b:e6:1a:c9:56:58:d7:e8:92:1d:63
jei-1.16.4-7.6.0.62.jar |Just Enough Items |jei |7.6.0.62 |DONE |NOSIGNATURE
Crash Report UUID: bc851c3d-4f5f-43c5-be70-5b643afe300b
Player Count: 1 / 8; [ServerPlayerEntity['Ajzaklija'/1409, l='ServerLevel[jasta ba]', x=-143.96, y=69.00, z=201.34]]
Data Packs: vanilla, mod:dungeoncrawl, mod:mutantbeasts (incompatible), mod:forge, mod:looot, mod:fastleafdecay (incompatible), mod:bettermineshafts (incompatible), mod:workshopsofdoom, mod:futurepack, mod:jei
Type: Integrated Server (map_client.txt)
Is Modded: Definitely; Client brand changed to 'forge'

I was not able to reproduce this.