I have been playing with my friend on a LAN server, but after 10-15 minutes it just crashes to the desktop and writing: An unknown error has occured...

Here is the crash-report: 

 

 

---- Minecraft Crash Report ----

WARNING: coremods are present:
Contact their authors BEFORE contacting forge

// Would you like a cupcake?

Time: 10/14/18 8:10 PM
Description: Unexpected error

java.lang.ClassCastException: net.minecraft.client.entity.EntityPlayerSP cannot be cast to net.minecraft.entity.player.EntityPlayerMP
    at alexndr.plugins.netherrocks.helpers.FyriteHandler.onItemUse(FyriteHandler.java:195)
    at alexndr.plugins.netherrocks.items.FyriteSword.func_180614_a(FyriteSword.java:36)
    at net.minecraft.item.ItemStack.func_179546_a(ItemStack.java:187)
    at net.minecraft.client.multiplayer.PlayerControllerMP.func_187099_a(PlayerControllerMP.java:477)
    at net.optifine.override.PlayerControllerOF.func_187099_a(PlayerControllerOF.java:96)
    at net.minecraft.client.Minecraft.func_147121_ag(Minecraft.java:1577)
    at net.minecraft.client.Minecraft.func_184117_aA(Minecraft.java:2252)
    at net.minecraft.client.Minecraft.func_184118_az(Minecraft.java:2018)
    at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1806)
    at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1096)
    at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:397)
    at net.minecraft.client.main.Main.main(SourceFile:123)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

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

-- Head --
Thread: Client thread
Stacktrace:
    at alexndr.plugins.netherrocks.helpers.FyriteHandler.onItemUse(FyriteHandler.java:195)
    at alexndr.plugins.netherrocks.items.FyriteSword.func_180614_a(FyriteSword.java:36)
    at net.minecraft.item.ItemStack.func_179546_a(ItemStack.java:187)
    at net.minecraft.client.multiplayer.PlayerControllerMP.func_187099_a(PlayerControllerMP.java:477)
    at net.optifine.override.PlayerControllerOF.func_187099_a(PlayerControllerOF.java:96)
    at net.minecraft.client.Minecraft.func_147121_ag(Minecraft.java:1577)
    at net.minecraft.client.Minecraft.func_184117_aA(Minecraft.java:2252)
    at net.minecraft.client.Minecraft.func_184118_az(Minecraft.java:2018)

-- Affected level --
Details:
    Level name: MpServer
    All players: 2 total; [EntityPlayerSP['ZajacStudio'/3551, l='MpServer', x=263.15, y=16.00, z=-52.56], EntityOtherPlayerMP['theBigKenny1'/16344, l='MpServer', x=241.50, y=11.00, z=-91.70]]
    Chunk stats: MultiplayerChunkCache: 289, 289
    Level seed: 0
    Level generator: ID 00 - default, ver 1. Features enabled: false
    Level generator options: 
    Level spawn location: World: (204,64,148), Chunk: (at 12,4,4 in 12,9; contains blocks 192,0,144 to 207,255,159), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
    Level time: 513710 game time, 588005 day time
    Level dimension: 0
    Level storage version: 0x00000 - Unknown?
    Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
    Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
    Forced entities: 83 total; [EntitySheep['Sheep'/3584, l='MpServer', x=219.80, y=67.00, z=-101.55], EntityRocketCreeper['Rocket Creeper'/101633, l='MpServer', x=281.22, y=50.00, z=-103.50], MoCEntityBee['Bee'/57345, l='MpServer', x=326.10, y=64.00, z=-99.66], MoCEntityCod['Cod'/3587, l='MpServer', x=244.85, y=62.00, z=-128.85], EntityRocketCreeper['Rocket Creeper'/55307, l='MpServer', x=286.32, y=20.00, z=-58.48], EntitySheep['Sheep'/3600, l='MpServer', x=216.23, y=65.00, z=-120.48], MoCEntityManderin['Manderin'/3604, l='MpServer', x=225.85, y=62.14, z=-132.15], MoCEntityFishy['Fishy'/62996, l='MpServer', x=337.06, y=61.49, z=-47.74], EntityZombie['Zombie'/104730, l='MpServer', x=290.50, y=56.00, z=-92.50], EntityTreasureSlime['Treasure Slime'/101927, l='MpServer', x=256.96, y=26.00, z=-133.70], EntitySkeletonWarrior['Skeleton Warrior'/101931, l='MpServer', x=199.50, y=41.00, z=-132.50], EntitySkeletonWarrior['Skeleton Warrior'/101933, l='MpServer', x=249.50, y=49.00, z=-31.50], MoCEntityAngelFish['AngelFish'/3630, l='MpServer', x=204.52, y=62.13, z=-116.64], MoCEntityKitty['Kitty'/3631, l='MpServer', x=207.19, y=62.91, z=-127.28], MoCEntityGoldFish['GoldFish'/3632, l='MpServer', x=206.85, y=62.00, z=-117.55], EntitySkeleton['Skeleton'/17202, l='MpServer', x=300.27, y=24.00, z=-55.49], EntityEnchantedBook['Bewitched Tome'/90932, l='MpServer', x=280.50, y=26.00, z=-101.16], EntityChameleon['Chameleon'/78135, l='MpServer', x=237.50, y=67.00, z=-50.50], EntityChicken['Chicken'/88385, l='MpServer', x=185.50, y=70.00, z=-20.48], EntitySupportCreeper['Support Creeper'/105796, l='MpServer', x=250.50, y=56.00, z=3.50], EntityEnchantedBook['Bewitched Tome'/43082, l='MpServer', x=299.50, y=28.00, z=-123.50], MoCEntityMaggot['Maggot'/84567, l='MpServer', x=215.50, y=67.00, z=-23.50], EntitySupportCreeper['Support Creeper'/84566, l='MpServer', x=223.50, y=39.00, z=-27.50], EntityHauntedTool['Haunted Tool'/82268, l='MpServer', x=298.50, y=48.00, z=-131.50], EntityFestiveCreeper['Festive Creeper'/90468, l='MpServer', x=299.50, y=49.00, z=-115.50], EntityOtherPlayerMP['theBigKenny1'/16344, l='MpServer', x=241.50, y=11.00, z=-91.70], EntityTreasureSlime['Treasure Slime'/60271, l='MpServer', x=244.76, y=39.00, z=-96.79], MoCEntityRoach['Roach'/84593, l='MpServer', x=249.10, y=72.00, z=-19.30], MoCEntityFly['Fly'/84594, l='MpServer', x=237.90, y=70.00, z=-11.62], EntityHauntedTool['Haunted Tool'/87929, l='MpServer', x=240.49, y=38.00, z=-97.07], EntityEnchantedBook['Bewitched Tome'/89468, l='MpServer', x=319.50, y=26.00, z=-127.50], EntityFestiveCreeper['Festive Creeper'/31614, l='MpServer', x=285.50, y=20.00, z=-61.50], EntityRocketCreeper['Rocket Creeper'/105603, l='MpServer', x=321.50, y=27.00, z=-120.50], EntityFestiveCreeper['Festive Creeper'/105606, l='MpServer', x=265.50, y=51.00, z=11.50], EntityFestiveCreeper['Festive Creeper'/105609, l='MpServer', x=342.50, y=40.00, z=12.50], EntityEnchantedBook['Bewitched Tome'/102795, l='MpServer', x=281.19, y=26.00, z=-39.53], EntitySpider['Spider'/78986, l='MpServer', x=293.70, y=33.10, z=-122.30], EntitySupportCreeper['Support Creeper'/105613, l='MpServer', x=297.50, y=19.00, z=-104.50], MoCEntityLion['Lion'/3731, l='MpServer', x=341.33, y=62.61, z=-70.59], MoCEntityLion['Lion'/3732, l='MpServer', x=339.18, y=62.61, z=-74.69], MoCEntityAnt['Ant'/3733, l='MpServer', x=325.19, y=67.00, z=-58.04], MoCEntityCricket['Cricket'/90521, l='MpServer', x=184.46, y=69.00, z=3.10], MoCEntityAnt['Ant'/3737, l='MpServer', x=309.53, y=68.00, z=-53.00], MoCEntityAnt['Ant'/3742, l='MpServer', x=298.50, y=69.00, z=-60.50], MoCEntityMaggot['Maggot'/3743, l='MpServer', x=291.50, y=69.00, z=-63.81], EntityWolf['Wolf'/90529, l='MpServer', x=286.45, y=72.00, z=15.91], MoCEntityBee['Bee'/3232, l='MpServer', x=252.57, y=73.00, z=24.49], MoCEntitySnake['Snake'/3746, l='MpServer', x=335.32, y=62.56, z=-102.70], MoCEntityDuck['Duck'/3747, l='MpServer', x=323.73, y=64.00, z=-106.17], EntityFestiveCreeper['Festive Creeper'/61609, l='MpServer', x=216.50, y=19.00, z=-83.50], MoCEntityRoach['Roach'/3248, l='MpServer', x=304.56, y=68.00, z=22.41], MoCEntityHorse['WildHorse'/3764, l='MpServer', x=317.96, y=61.62, z=-106.33], MoCEntityLion['Lion'/3765, l='MpServer', x=291.79, y=70.00, z=-66.29], EntityChicken['Chicken'/90556, l='MpServer', x=345.20, y=65.00, z=11.70], MoCEntityLion['Lion'/3780, l='MpServer', x=250.40, y=66.00, z=-51.24], EntitySkeletonWarrior['Skeleton Warrior'/25542, l='MpServer', x=311.50, y=25.00, z=-117.29], EntityZombie['Zombie'/93639, l='MpServer', x=302.50, y=45.00, z=-104.50], EntityChameleon['Chameleon'/99278, l='MpServer', x=201.77, y=67.00, z=-92.50], EntityChameleon['Chameleon'/99281, l='MpServer', x=304.50, y=70.00, z=-79.50], EntityOtherPlayerMP['theBigKenny1'/16344, l='MpServer', x=241.50, y=11.00, z=-91.70], EntitySupportCreeper['Support Creeper'/66781, l='MpServer', x=198.50, y=30.00, z=-129.50], EntityZombieVillager['Zombie Villager'/62949, l='MpServer', x=273.50, y=60.00, z=-45.50], EntityTreasureSlime['Treasure Slime'/62950, l='MpServer', x=265.38, y=44.00, z=-41.20], MoCEntityLion['Lion'/3559, l='MpServer', x=300.16, y=63.00, z=-117.35], MoCEntityLion['Lion'/62951, l='MpServer', x=271.11, y=79.00, z=-47.00], MoCEntityBird['Bird'/3815, l='MpServer', x=328.30, y=63.03, z=-121.37], MoCEntityTurtle['Turtle'/3816, l='MpServer', x=268.16, y=62.28, z=-118.97], EntitySkeletonWarrior['Skeleton Warrior'/81388, l='MpServer', x=311.50, y=22.00, z=-103.50], MoCEntityHorse['WildHorse'/3821, l='MpServer', x=205.03, y=67.00, z=-49.96], MoCEntityBass['Bass'/3566, l='MpServer', x=241.30, y=62.00, z=-116.30], MoCEntityCricket['Cricket'/3822, l='MpServer', x=211.00, y=66.00, z=-60.47], EntityEnchantedBook['Bewitched Tome'/101103, l='MpServer', x=216.50, y=16.00, z=-55.50], MoCEntityDuck['Duck'/3823, l='MpServer', x=248.57, y=62.71, z=-105.08], EntityItem['item.item.string'/57327, l='MpServer', x=252.50, y=47.00, z=-99.83], MoCEntityAnt['Ant'/3824, l='MpServer', x=237.50, y=64.00, z=-86.50], MoCEntityAnt['Ant'/3825, l='MpServer', x=239.50, y=64.00, z=-84.50], EntityPlayerSP['ZajacStudio'/3551, l='MpServer', x=263.15, y=16.00, z=-52.56], MoCEntityBird['Bird'/3571, l='MpServer', x=247.06, y=66.00, z=-92.64], MoCEntityBlackBear['BlackBear'/62970, l='MpServer', x=332.08, y=65.00, z=-40.27], MoCEntityBlackBear['BlackBear'/62971, l='MpServer', x=313.57, y=67.00, z=-45.89], EntityFestiveCreeper['Festive Creeper'/62973, l='MpServer', x=298.50, y=25.00, z=-42.50], EntityChameleon['Chameleon'/104444, l='MpServer', x=199.50, y=67.00, z=-70.50], EntityChameleon['Chameleon'/104446, l='MpServer', x=235.50, y=64.00, z=-86.50]]
    Retry entities: 0 total; []
    Server brand: fml,forge
    Server type: Integrated singleplayer server
Stacktrace:
    at net.minecraft.client.multiplayer.WorldClient.func_72914_a(WorldClient.java:532)
    at net.minecraft.client.Minecraft.func_71396_d(Minecraft.java:2738)
    at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:426)
    at net.minecraft.client.main.Main.main(SourceFile:123)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

-- System Details --
Details:
    Minecraft Version: 1.12.2
    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: 244391568 bytes (233 MB) / 1073741824 bytes (1024 MB) up to 1073741824 bytes (1024 MB)
    JVM Flags: 8 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=16M
    IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
    FML: MCP 9.42 Powered by Forge 14.23.3.2700 Optifine OptiFine_1.12.2_HD_U_E2 21 mods loaded, 21 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         | forge-1.12.2-14.23.3.2700.jar                 | e3c3d50c7c986df74c645c0ac54639741c90a557 |
    | UCHIJAAAA | forge          | 14.23.3.2700      | forge-1.12.2-14.23.3.2700.jar                 | e3c3d50c7c986df74c645c0ac54639741c90a557 |
    | UCHIJAAAA | babymobs       | 1.5.5             | Baby-Mobs-Mod-1.12.jar                        | None                                     |
    | UCHIJAAAA | biomesoplenty  | 7.0.1.2361        | BiomesOPlenty-1.12.2-7.0.1.2361-universal.jar | None                                     |
    | UCHIJAAAA | corerm         | 1.3.0             | RikMuldsCore-1.12.2.jar                       | None                                     |
    | UCHIJAAAA | camping        | 2.4.0             | Camping-Mod-1.12.2.jar                        | None                                     |
    | UCHIJAAAA | customspawner  | 3.11.4            | Custom-Mob-Spawner-Mod-1.12.2.jar             | None                                     |
    | UCHIJAAAA | erebus         | 1.0.22            | Erebus-Dimension-Mod-1.12.2.jar               | None                                     |
    | UCHIJAAAA | ironchest      | 1.12.2-7.0.46.831 | Iron-Chests-Mod-1.12.2.jar                    | None                                     |
    | UCHIJAAAA | jei            | 4.12.0.216        | jei_1.12.2-4.12.0.216.jar                     | None                                     |
    | UCHIJAAAA | lucky          | 7.5.0             | Lucky-Block-Mod-1.12.zip                      | None                                     |
    | UCHIJAAAA | mocreatures    | 12.0.5            | Mo-Creatures-Mod-1.12.2.jar                   | None                                     |
    | UCHIJAAAA | simplecore     | 1.7.2.13          | SimpleCore-API-1.12.2.jar                     | None                                     |
    | UCHIJAAAA | netherrocks    | 1.7.0.93          | Netherrocks-Mod-1.12.2.jar                    | None                                     |
    | UCHIJAAAA | primitivemobs  | 1.1.1             | Primitive-Mobs-Mod-1.12.2.jar                 | None                                     |
    | UCHIJAAAA | torohealthmod  | 1.12.2-11         | ToroCrafts-Damage-Indicators-Mod-1.12.2.jar   | None                                     |
    | UCHIJAAAA | treechopper    | 1.2.4             | Tree-Chopper-Mod-1.12.2.jar                   | None                                     |
    | UCHIJAAAA | twilightforest | 3.7.424           | Twilight-Forest-Mod-1.12.2.jar                | None                                     |
    | UCHIJAAAA | xaerominimap   | 1.13.9            | Xaeros-Minimap-Mod-1.12.jar                   | None                                     |

    Loaded coremods (and transformers): 
    GL info: ' Vendor: 'NVIDIA Corporation' Version: '4.6.0 NVIDIA 416.34' Renderer: 'GeForce GTX 1080/PCIe/SSE2'
    Launched Version: 1.12.2-forge1.12.2-14.23.3.2700
    LWJGL: 2.9.4
    OpenGL: GeForce GTX 1080/PCIe/SSE2 GL version 4.6.0 NVIDIA 416.34, NVIDIA Corporation
    GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

    Using VBOs: Yes
    Is Modded: Definitely; Client brand changed to 'fml,forge'
    Type: Client (map_client.txt)
    Resource Packs: 
    Current Language: English (US)
    Profiler Position: N/A (disabled)
    CPU: 12x AMD Ryzen 5 2600 Six-Core Processor 
    OptiFine Version: OptiFine_1.12.2_HD_U_E2
    OptiFine Build: 20180728-185429
    Render Distance Chunks: 8
    Mipmaps: 4
    Anisotropic Filtering: 1
    Antialiasing: 0
    Multitexture: false
    Shaders: SEUS-v10.1-Ultra.zip
    OpenGlVersion: 4.6.0 NVIDIA 416.34
    OpenGlRenderer: GeForce GTX 1080/PCIe/SSE2
    OpenGlVendor: NVIDIA Corporation
    CpuCount: 12

8 minutes ago, MinecraftNerd1234 said:

java.lang.ClassCastException: net.minecraft.client.entity.EntityPlayerSP cannot be cast to net.minecraft.entity.player.EntityPlayerMP
    at alexndr.plugins.netherrocks.helpers.FyriteHandler.onItemUse(FyriteHandler.java:195)

I would try removing the netherrocks mod and see if it still crashes.