Title says it all, following this guide and when I click 'run' in eclipse, it'll launch, try to load, and then crash.

 

Crash report is as follows:

---- Minecraft Crash Report ----
// I bet Cylons wouldn't have this problem.

Time: 12/9/20 11:54 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 Forge Mod Loader (FML)
Caused by: java.lang.NullPointerException
	at net.minecraftforge.fml.common.network.NetworkRegistry.newChannel(NetworkRegistry.java:207)
	at net.minecraftforge.fml.common.network.internal.FMLNetworkHandler.registerChannel(FMLNetworkHandler.java:185)
	at net.minecraftforge.fml.common.FMLContainer.modConstruction(FMLContainer.java:92)
	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 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$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
	at com.google.common.eventbus.EventBus.post(EventBus.java:217)
	at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:219)
	at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:197)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
	at com.google.common.eventbus.Subscriber$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:136)
	at net.minecraftforge.fml.common.Loader.loadMods(Loader.java:595)
	at net.minecraftforge.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:232)
	at net.minecraft.client.Minecraft.init(Minecraft.java:467)
	at net.minecraft.client.Minecraft.run(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)
	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.minecraftforge.legacydev.Main.start(Main.java:86)
	at net.minecraftforge.legacydev.MainClient.main(MainClient.java:29)


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_271, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 339201504 bytes (323 MB) / 875560960 bytes (835 MB) up to 3803185152 bytes (3627 MB)
	JVM Flags: 0 total; 
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	FML: MCP 9.42 Powered by Forge 14.23.5.2854 5 mods loaded, 5 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 |
	|:----- |:---------- |:------------ |:----------------------------------------------------------- |:--------- |
	| LC    | minecraft  | 1.12.2       | minecraft.jar                                               | None      |
	| LC    | mcp        | 9.42         | minecraft.jar                                               | None      |
	| LE    | FML        | 8.0.99.99    | forge-1.12.2-14.23.5.2854_mapped_snapshot_20171003-1.12.jar | None      |
	| L     | forge      | 14.23.5.2854 | forge-1.12.2-14.23.5.2854_mapped_snapshot_20171003-1.12.jar | None      |
	| L     | examplemod | 1.0          | main                                                        | None      |

	Loaded coremods (and transformers): 
	GL info: ' Vendor: 'NVIDIA Corporation' Version: '4.6.0 NVIDIA 457.51' Renderer: 'GeForce GTX 1050 Ti/PCIe/SSE2'

 

This forum only supports the newest versions of Forge, you need to upgrade to 1.15.X (preferably 1.16.X) to recieve support. There's a lot of tutorials out there for 1.15 and later, it's not difficult to find one.