So basically I have been trying to figure out why Forge keeps crashing when it is finalizing and the last the that is loaded is NEI and when it does crash the message: The game crashed whilst there was a severe problem during mod loading that has caused the game to fail
Error: net.minecraftforge.fml.common.LoaderExceptionModCrash: Caught exception from Not Enough Items (nei)

I've already tried to downloading different versions of Forge 1.12.2 but whenever I try to do this, something about "fml.messages.mod.missing.dependencies" appears. I have gone to different websites and dowloaded different variations of chicken lib 1.12.2 or NEI 1.12.2 but the first Error always occurs. The crash log:

---- Minecraft Crash Report ----

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

// Why is it breaking :(

Time: 10/8/18 8:42 PM
Description: There was a severe problem during mod loading that has caused the game to fail

net.minecraftforge.fml.common.LoaderExceptionModCrash: Caught exception from Not Enough Items (nei)
Caused by: java.lang.IllegalAccessError: tried to access class net.minecraft.potion.PotionHelper$MixPredicate from class codechicken.nei.util.helper.potion.PotionRecipeHelper
at codechicken.nei.util.helper.potion.PotionRecipeHelper.init(PotionRecipeHelper.java:60)
at codechicken.nei.init.NEIInitialization.bootNEI(NEIInitialization.java:70)
at codechicken.nei.proxy.ProxyClient.loadComplete(ProxyClient.java:54)
at codechicken.nei.NotEnoughItems.loadComplete(NotEnoughItems.java:63)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at net.minecraftforge.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:624)
at sun.reflect.GeneratedMethodAccessor18.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150)
at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76)
at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399)
at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71)
at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
at com.google.common.eventbus.EventBus.post(EventBus.java:217)
at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:218)
at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:196)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150)
at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76)
at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399)
at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71)
at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
at com.google.common.eventbus.EventBus.post(EventBus.java:217)
at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:135)
at net.minecraftforge.fml.common.Loader.initializeMods(Loader.java:752)
at net.minecraftforge.fml.client.FMLClientHandler.finishMinecraftLoading(FMLClientHandler.java:336)
at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:534)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:377)
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:

-- 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: 146851328 bytes (140 MB) / 603979776 bytes (576 MB) up to 3221225472 bytes (3072 MB)
JVM Flags: 8 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx3G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=16M
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
FML: MCP 9.42 Powered by Forge 14.23.5.2769 Optifine OptiFine_1.12.2_HD_U_E2 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                                |
|:------- |:-------------- |:------------ |:--------------------------------------------- |:---------------------------------------- |
| UCHIJA  | minecraft      | 1.12.2       | minecraft.jar                                 | None                                     |
| UCHIJA  | mcp            | 9.42         | minecraft.jar                                 | None                                     |
| UCHIJA  | FML            | 8.0.99.99    | forge-1.12.2-14.23.5.2769.jar                 | e3c3d50c7c986df74c645c0ac54639741c90a557 |
| UCHIJA  | forge          | 14.23.5.2769 | forge-1.12.2-14.23.5.2769.jar                 | e3c3d50c7c986df74c645c0ac54639741c90a557 |
| UCHIJA  | codechickenlib | 3.2.2.353    | CodeChickenLib-1.12.2-3.2.2.353-universal.jar | f1850c39b2516232a2108a7bd84d1cb5df93b261 |
| UCHIJA  | jei            | 4.12.1.217   | jei_1.12.2-4.12.1.217.jar                     | None                                     |
| UCHIJEE | nei            | 2.4.1        | NotEnoughItems-1.12.2-2.4.1.239-universal.jar | f1850c39b2516232a2108a7bd84d1cb5df93b261 |

Loaded coremods (and transformers): 
GL info: ' Vendor: 'ATI Technologies Inc.' Version: '4.5.14009 Compatibility Profile Context 21.19.144.1281' Renderer: 'AMD Radeon R7'
OptiFine Version: OptiFine_1.12.2_HD_U_E2
OptiFine Build: 20180728-185429
Render Distance Chunks: 12
Mipmaps: 4
Anisotropic Filtering: 1
Antialiasing: 0
Multitexture: false
Shaders: null
OpenGlVersion: 4.5.14009 Compatibility Profile Context 21.19.144.1281
OpenGlRenderer: AMD Radeon R7
OpenGlVendor: ATI Technologies Inc.
CpuCount: 4

Use build 240 from here: http://chickenbones.net/Pages/links.html. I had the same crash with build 239. 240 fixed it. I'm using Forge 2768

Duplicate of #183