Fixed crash when rendering empty active beacon cluster bing after loa…

…ding (due to handler ref being nullptr).

Also added error message for loading nonexisting level number (instead of assertion and termination).
Finally let's see how AppVeyor deployment works...

EditorInterface.cpp

@@ -1082,7 +1082,7 @@ void EditorInterface::render()
 		if (showBeacons) {
 			uint32_t fallbackSphereColor = 255 - (SDL_GetTicks() % 1000) * 128 / 1000;
 			for (auto &bing : bk->bings) {
-				if (!bing.active)
+				if (!bing.active || bing.beacons.empty())
 					continue;
 				uint32_t handlerFID = bing.handler->getClassFullID();
 				for (auto &beacon : bing.beacons) {
@@ -1525,24 +1525,33 @@ void EditorInterface::IGMain()
 	static int levelNum = 8;
 	ImGui::InputInt("Level number##LevelNum", &levelNum);
 	if (ImGui::Button("Load")) {
-		selGeometry = nullptr;
-		selNode = nullptr;
-		selBeaconSector = -1;
-		selGround = nullptr;
-		selectedSquad = nullptr;
-		selectedX2Squad = nullptr;
-		selectedPFGraphNode = nullptr;
-		selectedMarker = nullptr;
-		selectedHook = nullptr;
-		selectedTrigger = nullptr;
-		selClones.clear();
-		rayHits.clear();
-		nearestRayHit = nullptr;
-
-		progeocache.clear();
-		gndmdlcache.clear();
-		kenv.loadLevel(levelNum);
-		prepareLevelGfx();
+		const char* fnfmt = kenv.isUsingNewFilenames() ? "LVL%03u/LVL%03u.%s" : "LVL%03u/LVL%02u.%s";
+		char lvlfn[64];
+		snprintf(lvlfn, sizeof(lvlfn), fnfmt, levelNum, levelNum, kenv.platformExt[kenv.platform]);
+		if (!std::filesystem::exists(std::filesystem::u8path(kenv.gamePath) / lvlfn)) {
+			snprintf(lvlfn, sizeof(lvlfn), "Level %i does not exist.", levelNum);
+			MessageBox((HWND)g_window->getNativeWindow(), lvlfn, "XXL Editor", 16);
+		}
+		else {
+			selGeometry = nullptr;
+			selNode = nullptr;
+			selBeaconSector = -1;
+			selGround = nullptr;
+			selectedSquad = nullptr;
+			selectedX2Squad = nullptr;
+			selectedPFGraphNode = nullptr;
+			selectedMarker = nullptr;
+			selectedHook = nullptr;
+			selectedTrigger = nullptr;
+			selClones.clear();
+			rayHits.clear();
+			nearestRayHit = nullptr;
+
+			progeocache.clear();
+			gndmdlcache.clear();
+			kenv.loadLevel(levelNum);
+			prepareLevelGfx();
+		}
 	}
 	ImGui::SameLine();
 	if (ImGui::Button("Save")) {