fix(lwjgl): preserve org.lwjgl.system.Configuration static initializer

[ChipWolf]

Problem

Launching Minecraft 26.2 headlessly with the --lwjgl agent crashes on startup (exit 253), for all three modloaders (Fabric, NeoForge, LexForge):

Description: Loading native libraries
java.lang.NullPointerException: Cannot invoke "org.lwjgl.system.Configuration.get()"
  because "org.lwjgl.system.Configuration.SHARED_LIBRARY_EXTRACT_PATH" is null
	at com.mojang.blaze3d.platform.NativeLibrariesBootstrap.configureLWJGLLibraryPath(NativeLibrariesBootstrap.java:168)
	at com.mojang.blaze3d.platform.NativeLibrariesBootstrap.loadLibraries(NativeLibrariesBootstrap.java:64)
	at net.minecraft.client.main.Main.main(Main.java:131)

Root cause

LwjglTransformer transforms every org/lwjgl class by replacing all method bodies with redirection calls, including the static initializer (<clinit>). For org.lwjgl.system.Configuration this means its public static final Configuration<?> option fields are never assigned and stay null.

Minecraft 26.2 introduced com.mojang.blaze3d.platform.NativeLibrariesBootstrap, which reads Configuration.SHARED_LIBRARY_EXTRACT_PATH during native-library loading. Because the field is null, the client NPEs before the window opens. Earlier versions (26.1.x and below) never touched Configuration at bootstrap, so the gutted initializer was harmless — this only surfaces on 26.2+.

Fix

Leave org.lwjgl.system.Configuration untransformed. It is a pure configuration registry with no native calls, so it can safely run as-is. It then behaves exactly as it does in a real (non-headless) launch — where these fields are always populated — while every actual native/GL class stays stubbed.

Testing

• Added LwjglInstrumentationTest.testConfigurationStaticInitializerPreserved(), which loads a stub org.lwjgl.system.Configuration through the transformer and asserts its static field is non-null. Verified it fails without the guard (expected: not <null>) and passes with it.
• Full :headlessmc-lwjgl:test suite passes.

Context

Surfaced while adding Minecraft 26.2 support to headlesshq/mc-runtime-test (headlesshq/mc-runtime-test#137). The default xvfb path already works on 26.2; only the --lwjgl headless path hit this. Once released, mc-runtime-test can bump its hmc-version to pick this up.

🤖 Generated with Claude Code

[ChipWolf]

Closing in favour of #426, which I'd missed when I opened this — thanks @okafke. #426 reaches the same conclusion for the native-libraries crash (ignore org/lwjgl/system/Configuration) and goes further: it makes the ignore-list configurable, adds Platform, and handles the 26.2 GPUDevice/DeviceLimits redirections that this minimal patch would have crashed on next. #426 is the complete fix.

If it's useful, the regression test I added here (LwjglInstrumentationTest loading a stub org.lwjgl.system.Configuration and asserting its static field survives transformation) is easy to lift over, but no worries either way.