The bug

When LWJGL is in debug mode, it checks for null pointers. This breaks the forced JVM crash, which uses MemoryUtil.memSet(0L, 0, 1L) which performs such a check.

How to reproduce

1. Add -Dorg.lwjgl.util.Debug=true to the JVM arguments to enable LWJGL debug mode.
2. Hold right control+F3+C
3. The game will crash with the attached report with an java.lang.IllegalArgumentException. The JVM will not crash.

(note: if you get a regular "Manually triggered debug crash", then the forced JVM crash did not trigger due to MC-135509; that is not this issue).

Fix:

Use a memory address other than 0. For instance, 1 would be fine, and in this case memPutByte could be used (which normally wouldn't work as memPutByte always checks for null pointers, which is why I assume memSet was used). Alternatively, 0xDEADBEEF would be recognizable as an intended debug value.