I just updated my game, and whenever I start my game, even if I make a new directory, my game always crashes on startup, it may have to do with the slabs change, I do not know, but here is the crash report:

---- Minecraft Crash Report ----

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

// Don't be sad, have a hug! <3 ok thanks!

Time: 7/30/20 4:16 PM
Description: Initializing game

java.lang.NoClassDefFoundError: scala/actors/threadpool/Arrays
    at com.swdteam.common.init.DMBlocks.setupSlabItems(DMBlocks.java:606)
    at com.swdteam.common.init.DMBlocks.regBlocks(DMBlocks.java:588)
    at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_20_DMBlocks_regBlocks_Register.invoke(.dynamic)
    at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
    at net.minecraftforge.fml.common.eventhandler.EventBus$1.invoke(EventBus.java:144)
    at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:182)
    at net.minecraftforge.registries.GameData.fireRegistryEvents(GameData.java:845)
    at net.minecraftforge.fml.common.Loader.preinitializeMods(Loader.java:630)
    at net.minecraftforge.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:252)
    at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:467)
    at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:378)
    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:498)
    at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
Caused by: java.lang.ClassNotFoundException: scala.actors.threadpool.Arrays
    at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 18 more
Caused by: java.lang.NullPointerException


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

-- Head --
Thread: Client thread
Stacktrace:
    at com.swdteam.common.init.DMBlocks.setupSlabItems(DMBlocks.java:606)
    at com.swdteam.common.init.DMBlocks.regBlocks(DMBlocks.java:588)
    at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_20_DMBlocks_regBlocks_Register.invoke(.dynamic)
    at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
    at net.minecraftforge.fml.common.eventhandler.EventBus$1.invoke(EventBus.java:144)
    at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:182)
    at net.minecraftforge.registries.GameData.fireRegistryEvents(GameData.java:845)
    at net.minecraftforge.fml.common.Loader.preinitializeMods(Loader.java:630)
    at net.minecraftforge.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:252)
    at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:467)

-- Initialization --
Details:
Stacktrace:
    at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:378)
    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:498)
    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: Mac OS X (x86_64) version 10.13.6
    Java Version: 1.8.0_151, Oracle Corporation
    Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
    Memory: 222923240 bytes (212 MB) / 1078984704 bytes (1029 MB) up to 4779933696 bytes (4558 MB)
    JVM Flags: 3 total; -Xmx5128m -Xms256m -XX:PermSize=256m
    IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
    FML: MCP 9.42 Powered by Forge 14.23.5.2854 Optifine OptiFine_1.12.2_HD_U_F5 7 mods loaded, 7 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                                |
    |:----- |:----------- |:--------------- |:--------------------------------------------- |:---------------------------------------- |
    | LCH   | minecraft   | 1.12.2          | minecraft.jar                                 | None                                     |
    | LCH   | mcp         | 9.42            | minecraft.jar                                 | None                                     |
    | LCH   | FML         | 8.0.99.99       | forge-1.12.2-14.23.5.2854.jar                 | e3c3d50c7c986df74c645c0ac54639741c90a557 |
    | LCH   | forge       | 14.23.5.2854    | forge-1.12.2-14.23.5.2854.jar                 | e3c3d50c7c986df74c645c0ac54639741c90a557 |
    | LCH   | thedalekmod | (Update 58.1.0) | dm-58.1.jar                                   | None                                     |
    | LCH   | jei         | 4.15.0.287      | jei_1.12.2-4.15.0.287.jar                     | None                                     |
    | LCH   | journeymap  | 1.12.2-5.5.4    | journeymap-1.12.2-5.5.4 17.09.06 17.09.06.jar | None                                     |

    Loaded coremods (and transformers):
    GL info: ' Vendor: 'ATI Technologies Inc.' Version: '2.1 ATI-1.68.20' Renderer: 'AMD Radeon Pro 455 OpenGL Engine'
    Launched Version: forge-14.23.5.2854
    LWJGL: 2.9.2
    OpenGL: AMD Radeon Pro 455 OpenGL Engine GL version 2.1 ATI-1.68.20, ATI Technologies Inc.
    GL Caps: VboRegions not supported, missing: OpenGL 1.3, ARB_copy_buffer
Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because ARB_framebuffer_object 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: 8x Intel(R) Core(TM) i7-6820HQ CPU @ 2.70GHz
    OptiFine Version: OptiFine_1.12.2_HD_U_F5
    OptiFine Build: 20191204-141934
    Render Distance Chunks: 10
    Mipmaps: 4
    Anisotropic Filtering: 1
    Antialiasing: 0
    Multitexture: false
    Shaders: null
    OpenGlVersion: 2.1 ATI-1.68.20
    OpenGlRenderer: AMD Radeon Pro 455 OpenGL Engine
    OpenGlVendor: ATI Technologies Inc.
    CpuCount: 8

i got same problem too im very annoyed about it i wanna play some but whenever i trie 58 version it works but i cant play multiplayer :( anyone got a fix

 It doesn't work for me, i even tried a fresh Minecraft directory, but it didn't work sadly.

Redownload the mod here: https://www.curseforge.com/minecraft/mc-mods/the-dalek-mod/download/3019672

if anyone wants to have a bit of an idea of what is going on here is a link https://swdteam.com/forum?p=thread&tid=8371&page=1#t_post_id_53152

also thanks weirdo, I dunno if you are a weirdo, but your name says so.

 thanks, it works, wooo! Thanks weirdo for telling me!