bugfix(debug): Skip system-modal crash dialogs in headless runs

[bobtista]

• Closes Headless runs block on system-modal dialogs after fatal errors #3029

ReleaseCrash and ReleaseCrashLocalized call MessageBox even when the game runs with -headless. The system-modal dialog blocks _exit(1), leaving an unattended process alive until somebody dismisses it.

Now only the dialog calls are skipped when TheGlobalData->m_headless is set. Crash reporting, minidump generation, and _exit(1) remain unchanged.

Todo:

• Confirm -headless is parsed before subsystem initialization failures
• Verify a -headless initialization failure exits 1, writes ReleaseCrashInfo.txt, and shows no UI
• Verify the same failure without -headless retains the existing dialog
• Verify a successful -headless run remains unaffected
• Replicate to Generals — N/A, it's in Core

Verification (Windows, MSVC x86)

Built z_generals in both win32-debug (RTS_DEBUG) and win32 Release so both sides of the #if defined(RTS_DEBUG) split are covered. A subsystem initialization failure was induced by putting an invalid Bool (UseTrees = Maybe) in the install's loose Data\INI\GameData.ini, which makes INI::scanBool throw, gets rethrown as INIException, and lands in GameEngine::init's catch (INIException) handler.

Case	Debug	Release
Headless failure	exit 1, ReleaseCrashInfo.txt written, no window	exit 1, ReleaseCrashInfo.txt written, no window
Same failure without -headless	"Technical Difficulties..." dialog shown, exit 1 after OK	"Technical Difficulties..." dialog shown, exit 1 after OK
Successful headless run (-replay ... -headless)	exit 0	exit 0

Pre-fix control: reverting Debug.cpp and rebuilding reproduces #3029 — the headless process stays alive on a visible system-modal dialog with no game window, and only exits once the dialog is dismissed by hand.

-headless is parsed by parseCommandLineForStartup in WinMain before GameMain, so m_headless is already set when GameEngine::init loads INI data.

Note on TheGlobalData == nullptr

ReleaseCrash already returns early when TheGlobalData is null, before reaching either MessageBox, so crashes that early show no dialog at all today. The null check in the new guards is therefore only meaningful in ReleaseCrashLocalized, where the dialog precedes the first TheGlobalData dereference. It is kept in all three for consistency.

[greptile-apps]

Greptile Summary

This PR prevents crash dialogs from blocking unattended headless runs.

• Guards debug and release ReleaseCrash message boxes with the existing headless flag.
• Applies the same guard to the localized crash dialog.
• Leaves crash logging, minidump generation, and process termination unchanged.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
Core/GameEngine/Source/Common/System/Debug.cpp	Adds headless-mode guards around all system-modal crash dialogs without altering crash-reporting or termination paths.

_{Reviews (2): Last reviewed commit: "bugfix(system): Skip system-modal crash ..." | Re-trigger Greptile}

[xezon]

Code correct