I have reached an interesting point in a coremod that I am developing, when using the dev environment it works fine but when installed on a normal client it crashes as soon as it is about to render the main menu. It is a byte code verification error and I can not figure out a good way to debug why this is happening. I tried the ASM class verifier but that just causes a ton of ClassNotFoundExceptions.

 

Relevant chunk of the crash report:

java.lang.VerifyError: Bad local variable type
Exception Details:
  Location:
    net/minecraft/client/renderer/RenderHelper.func_74518_a()V @0: aload_0
  Reason:
    Type top (current frame, locals[0]) is not assignable to reference type
  Current Frame:
    bci: @0
    flags: { }
    locals: { }
    stack: { }
  Bytecode:
    0x0000000: 2a12 0eb8 0014 b600 1ab8 001f 03b8 0023
    0x0000010: 04b8 0023 b800 26b1                    

	at net.minecraft.client.gui.toasts.GuiToast.func_191783_a(SourceFile:32)
	at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1119)
	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(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)

 

And the entire thing for good measure:

---- Minecraft Crash Report ----

WARNING: coremods are present:
 [redacted]
Contact their authors BEFORE contacting forge

// Shall we play a game?

Time: 9/6/17 11:37 AM
Description: Unexpected error

java.lang.VerifyError: Bad local variable type
Exception Details:
 Location:
 net/minecraft/client/renderer/RenderHelper.func_74518_a()V @0: aload_0
 Reason:
 Type top (current frame, locals[0]) is not assignable to reference type
 Current Frame:
 bci: @0
 flags: { }
 locals: { }
 stack: { }
 Bytecode:
 0x0000000: 2a12 0eb8 0014 b600 1ab8 001f 03b8 0023
 0x0000010: 04b8 0023 b800 26b1 

 at net.minecraft.client.gui.toasts.GuiToast.func_191783_a(SourceFile:32)
 at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1119)
 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(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)


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

-- System Details --
Details:
 Minecraft Version: 1.12.1
 Operating System: Windows 10 (amd64) version 10.0
 Java Version: 1.8.0_144, Oracle Corporation
 Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
 Memory: 5447305032 bytes (5194 MB) / 6442450944 bytes (6144 MB) up to 10737418240 bytes (10240 MB)
 JVM Flags: 12 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx6144m -Xms256m -XX:PermSize=256m -XX:+UseG1GC -Xmx10G -Xms6G -XX:+UnlockExperimentalVMOptions -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
 IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
 FML: MCP 9.41 Powered by Forge 14.22.0.2469 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 |
 |:------ |:---------- |:------------ |:----------------------------- |:---------------------------------------- |
 | UCHIJA | minecraft | 1.12.1 | minecraft.jar | None |
 | UCHIJA | mcp | 9.19 | minecraft.jar | None |
 | UCHIJA | FML | 8.0.99.99 | forge-1.12.1-14.22.0.2469.jar | e3c3d50c7c986df74c645c0ac54639741c90a557 |
 | UCHIJA | forge | 14.22.0.2469 | forge-1.12.1-14.22.0.2469.jar | e3c3d50c7c986df74c645c0ac54639741c90a557 |
 | UCHIJA | [redacted] | | minecraft.jar | None |

 Loaded coremods (and transformers): 
[redacted]
 net.gudenau.[redacted]
 net.gudenau.[redacted]
 GL info: ' Vendor: 'NVIDIA Corporation' Version: '4.5.0 NVIDIA 382.05' Renderer: 'GeForce GTX 960/PCIe/SSE2'
 Launched Version: forge-14.22.0.2469
 LWJGL: 2.9.4 HACKED TO 3.1.2 build 29
 OpenGL: GeForce GTX 960/PCIe/SSE2 GL version 4.5.0 NVIDIA 382.05, 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: 4x Intel(R) Core(TM) i5-3570K CPU @ 3.40GHz

 

Don't make coremods.

20 minutes ago, LexManos said:

Don't make coremods.

Except that I need to do a core mod for this. This change will never get pulled into Forge.

Thats what they all say.

Also the only support you'll get here is to not make coremods.

If you don't know what you're doing, especially simple debugging, then you shouldn't be doing what you're doing.

24 minutes ago, LexManos said:

Thats what they all say.

Also the only support you'll get here is to not make coremods.

If you don't know what you're doing, especially simple debugging, then you shouldn't be doing what you're doing.

I am sorry that I do not know how to make a debugger attach to a normal instance and that when I read the bytecode my mod produces it looks normal. I can usually figure this crap out.