fix(debug): Simplify unconditional DEBUG_ASSERTCRASH to DEBUG_CRASH (#2067)

Replace DEBUG_ASSERTCRASH(nullptr, ...) with DEBUG_CRASH(...) for
unconditional crash assertions in MinGW-w64 debug builds.

Changes:
- PlayerTemplate.cpp: DEBUG_ASSERTCRASH(nullptr) → DEBUG_CRASH
- ChallengeGenerals.cpp: DEBUG_ASSERTCRASH(nullptr) → DEBUG_CRASH
- LoadScreen.cpp: 2× DEBUG_ASSERTCRASH(nullptr) → DEBUG_CRASH

Total: 4 instances simplified across GeneralsMD codebase

Rationale:
DEBUG_ASSERTCRASH(nullptr, ...) was causing compilation errors with
MinGW-w64 due to implicit nullptr-to-bool conversion. These instances
represent "unconditional crash" assertions (always false condition).

The DEBUG_CRASH macro is the semantically correct choice for this use
case, making the intent explicit and avoiding type conversion issues.

Error resolved:
  error: converting to 'bool' from 'std::nullptr_t' requires
  direct-initialization [-fpermissive]

Historical note: These instances were introduced by commit f891c5f
("refactor: Modernize NULL to nullptr"). The original NULL was
semantically 0 (false), not a null pointer check.

Affects: GeneralsMD debug builds only

Author: JohnsterID

GeneralsMD/Code/GameEngine/Source/Common/RTS/PlayerTemplate.cpp

@@ -294,7 +294,7 @@ Int PlayerTemplateStore::getTemplateNumByName(AsciiString name) const
 		if (m_playerTemplates[num].getName().compareNoCase(name.str()) == 0)
 			return num;
 	}
-	DEBUG_ASSERTCRASH(nullptr, ("Template doesn't exist for given name"));
+	DEBUG_CRASH(("Template doesn't exist for given name"));
 	return -1;
 }
 

GeneralsMD/Code/GameEngine/Source/GameClient/GUI/ChallengeGenerals.cpp

@@ -133,7 +133,7 @@ const GeneralPersona* ChallengeGenerals::getPlayerGeneralByCampaignName( AsciiSt
 		if (campaignName.compareNoCase( name.str() ) == 0)
 			return &m_position[i];
 	}
-	DEBUG_ASSERTCRASH(nullptr, ("Can't find General by Campaign Name"));
+	DEBUG_CRASH(("Can't find General by Campaign Name"));
 	return nullptr;
 }
 

GeneralsMD/Code/GameEngine/Source/GameClient/GUI/LoadScreen.cpp

@@ -1308,7 +1308,7 @@ void MultiPlayerLoadScreen::init( GameInfo *game )
 		else if (pt->getName() == "FactionChina")
 			portrait = TheMappedImageCollection->findImageByName("SNFactionLogoLg_China");
 		else
-			DEBUG_ASSERTCRASH(nullptr, ("Unexpected player template"));
+			DEBUG_CRASH(("Unexpected player template"));
 
 		localName = pt->getDisplayName();
 	}
@@ -1579,7 +1579,7 @@ GameSlot *lSlot = game->getSlot(game->getLocalSlotNum());
 		else if (pt->getName() == "FactionChina")
 			portrait = TheMappedImageCollection->findImageByName("SNFactionLogo144_China");
 		else
-			DEBUG_ASSERTCRASH(nullptr, ("Unexpected player template"));
+			DEBUG_CRASH(("Unexpected player template"));
 
 		localName = pt->getDisplayName();
 	}