Remove redundant devilutionx.mpq check

We now check it only once in `CheckArchivesUpToDate`.
We then use `LoadClx` instead of `LoadOptionalClx` throughout.

Source/diablo.cpp

@@ -943,13 +943,15 @@ void SetApplicationVersions()
 
 void CheckArchivesUpToDate()
 {
-	const bool devilutionxMpqOutOfDate = devilutionx_mpq && devilutionx_mpq->HasFile("fonts\\12-00.pcx");
-	const bool fontsMpqOutOfDate = font_mpq && font_mpq->HasFile("fonts\\12-4e.pcx");
+	const bool devilutionxMpqOutOfDate = devilutionx_mpq && !devilutionx_mpq->HasFile("data\\charbg.clx");
+	const bool fontsMpqOutOfDate = font_mpq && !font_mpq->HasFile("fonts\\12-4e.clx");
 
 	if (devilutionxMpqOutOfDate && fontsMpqOutOfDate) {
 		app_fatal(_("Please update devilutionx.mpq and fonts.mpq to the latest version"));
 	} else if (devilutionxMpqOutOfDate) {
-		app_fatal(_("Please update devilutionx.mpq to the latest version"));
+		app_fatal(_("Failed to load UI resources.\n"
+		            "\n"
+		            "Make sure devilutionx.mpq is in the game folder and that it is up to date."));
 	} else if (fontsMpqOutOfDate) {
 		app_fatal(_("Please update fonts.mpq to the latest version"));
 	}

Source/panels/charpanel.cpp

@@ -265,9 +265,7 @@ void DrawStatButtons(const Surface &out)
 
 void LoadCharPanel()
 {
-	OptionalOwnedClxSpriteList background = LoadOptionalClx("data\\charbg.clx");
-	if (!background)
-		app_fatal(_("Please update devilutionx.mpq to the latest version"));
+	OptionalOwnedClxSpriteList background = LoadClx("data\\charbg.clx");
 	OwnedSurface out((*background)[0].width(), (*background)[0].height());
 	RenderClxSprite(out, (*background)[0], { 0, 0 });
 	background = std::nullopt;

Source/panels/mainpanel.cpp

@@ -67,9 +67,7 @@ void LoadMainPanel()
 	std::optional<OwnedSurface> out;
 	constexpr uint16_t NumButtonSprites = 6;
 	{
-		OptionalOwnedClxSpriteList background = LoadOptionalClx("data\\panel8bucp.clx");
-		if (!background)
-			app_fatal(_("Please update devilutionx.mpq to the latest version"));
+		OptionalOwnedClxSpriteList background = LoadClx("data\\panel8bucp.clx");
 		out.emplace((*background)[0].width(), (*background)[0].height() * NumButtonSprites);
 		int y = 0;
 		for (ClxSprite sprite : ClxSpriteList(*background)) {

Source/qol/stash.cpp

@@ -268,14 +268,8 @@ void InitStash()
 {
 	InitialWithdrawGoldValue = 0;
 
-	StashPanelArt = LoadOptionalClx("data\\stash.clx");
-	StashNavButtonArt = LoadOptionalClx("data\\stashnavbtns.clx");
-
-	if (!StashPanelArt || !StashNavButtonArt) {
-		app_fatal(_("Failed to load UI resources.\n"
-		            "\n"
-		            "Make sure devilutionx.mpq is in the game folder and that it is up to date."));
-	}
+	StashPanelArt = LoadClx("data\\stash.clx");
+	StashNavButtonArt = LoadClx("data\\stashnavbtns.clx");
 }
 
 void TransferItemToInventory(Player &player, uint16_t itemId)

Source/qol/xpbar.cpp

@@ -52,13 +52,7 @@ void DrawEndCap(const Surface &out, Point point, int idx, const ColorGradient &g
 void InitXPBar()
 {
 	if (*sgOptions.Gameplay.experienceBar) {
-		xpbarArt = LoadOptionalClx("data\\xpbar.clx");
-
-		if (!xpbarArt) {
-			app_fatal(_("Failed to load UI resources.\n"
-			            "\n"
-			            "Make sure devilutionx.mpq is in the game folder and that it is up to date."));
-		}
+		xpbarArt = LoadClx("data\\xpbar.clx");
 	}
 }