Been lurking around for a while to try and find a solution to this problem with no luck. I've been following McJty's tutorial. And while I have big things envisioned, at the moment I'm just testing if I can add a single item into a creative tab. And while I've knocked out all the errors the IDE was throwing at me, trying to run the GradleStart gives me an error from the Client Proxy "Class not found" but the client proxy only points to one class inside of it and that class very much exists.
Mod coding:
https://github.com/Sarelm/Dynams/blob/master/Dynams.java

Crash Report:

Spoiler

---- Minecraft Crash Report ----
// Hi. I'm Minecraft, and I'm a crashaholic.

Time: 2/21/18 1:54 AM
Description: There was a severe problem during mod loading that has caused the game to fail

net.minecraftforge.fml.common.LoaderExceptionModCrash: Caught exception from Dynams (dynams)
Caused by: net.minecraftforge.fml.common.LoaderException: java.lang.ClassNotFoundException: sarelm.dynams.proxy.ClientProxy
    at net.minecraftforge.fml.common.ProxyInjector.inject(ProxyInjector.java:102)
    at net.minecraftforge.fml.common.FMLModContainer.constructMod(FMLModContainer.java:585)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    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$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
    at com.google.common.eventbus.EventBus.post(EventBus.java:217)
    at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:278)
    at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:256)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
    at com.google.common.eventbus.Subscriber$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:148)
    at net.minecraftforge.fml.common.Loader.loadMods(Loader.java:568)
    at net.minecraftforge.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:231)
    at net.minecraft.client.Minecraft.init(Minecraft.java:513)
    at net.minecraft.client.Minecraft.run(Minecraft.java:421)
    at net.minecraft.client.main.Main.main(Main.java:118)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    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(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at net.minecraftforge.gradle.GradleStartCommon.launch(GradleStartCommon.java:97)
    at GradleStart.main(GradleStart.java:26)
Caused by: java.lang.ClassNotFoundException: sarelm.dynams.proxy.ClientProxy
    at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at net.minecraftforge.fml.common.ModClassLoader.loadClass(ModClassLoader.java:75)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Unknown Source)
    at net.minecraftforge.fml.common.ProxyInjector.inject(ProxyInjector.java:85)
    ... 43 more
Caused by: java.lang.NullPointerException
    at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:182)
    ... 49 more

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_161, Oracle Corporation
    Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
    Memory: 904384544 bytes (862 MB) / 1171259392 bytes (1117 MB) up to 3806855168 bytes (3630 MB)
    JVM Flags: 0 total; 
    IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
    FML: MCP 9.42 Powered by Forge 14.23.1.2610 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 |
    |:----- |:--------- |:------------ |:-------------------------------- |:--------- |
    | UC    | minecraft | 1.12.2       | minecraft.jar                    | None      |
    | UC    | mcp       | 9.42         | minecraft.jar                    | None      |
    | UC    | FML       | 8.0.99.99    | forgeSrc-1.12.2-14.23.1.2610.jar | None      |
    | UC    | forge     | 14.23.1.2610 | forgeSrc-1.12.2-14.23.1.2610.jar | None      |
    | UE    | dynams    | 1.0          | bin                              | None      |

    Loaded coremods (and transformers): 
    GL info: ' Vendor: 'NVIDIA Corporation' Version: '4.6.0 NVIDIA 388.13' Renderer: 'GeForce GTX 1070/PCIe/SSE2'

 

Edited February 21, 20187 yr by Sarelm

Your project does not contain either a client or server proxy, yet you are telling Forge that you need them:

https://github.com/Sarelm/Dynams/blob/master/Dynams.java#L27-L28

Okay, back to tutorials then.

move ClientProxy and CommonProxy to two separate files then reference them properly

18 minutes ago, diesieben07 said:

There is no such thing as a "CommonProxy".

Agreed, look at his code though. I think that you should probably save that revelation for another day

Most modders use common proxies and almost all tutorials use them.

He should however read the docs

https://mcforge.readthedocs.io/en/latest/concepts/sides/#sidedproxy

http://jabelarminecraft.blogspot.com.au/p/minecraft-modding-organizing-your-proxy.html?m=1

I have read the docs, but it doesn't explain how to structure your mod. I've been following this tutorial https://wiki.mcjty.eu/modding/index.php?title=Basic_Mod-1.12
And then referencing others when my IDE threw up errors from it. Like a lack of a constructor. I'm going the other way about it now.

1 hour ago, Sarelm said:

I have read the docs, but it doesn't explain how to structure your mod. I've been following this tutorial https://wiki.mcjty.eu/modding/index.php?title=Basic_Mod-1.12

I fucking hate this:

 

    @Mod.EventHandler
    public void init(FMLInitializationEvent e) {
        proxy.init(e);
    }

    @Mod.EventHandler
    public void postInit(FMLPostInitializationEvent e) {
        proxy.postInit(e);
    }

NO. DON'T PASS OFF THE EVENTS TO YOUR PROXY. FUCK. JUST DO THE STUFF RIGHT HERE.