fix: Do not crash on unknown MAD manifesto format (R2Northstar#749)

Verify JSON has attributes before trying to access them

primedev/mods/autodownload/moddownloader.cpp

@@ -95,6 +95,13 @@ void ModDownloader::FetchModsListFromAPI()
 			verifiedModsJson.Parse(readBuffer);
 			for (auto i = verifiedModsJson.MemberBegin(); i != verifiedModsJson.MemberEnd(); ++i)
 			{
+				// Format testing
+				if (!i->value.HasMember("DependencyPrefix") || !i->value.HasMember("Versions"))
+				{
+					spdlog::warn("Verified mods manifesto format is unrecognized, skipping loading.");
+					return;
+				}
+
 				std::string name = i->name.GetString();
 				std::string dependency = i->value["DependencyPrefix"].GetString();
 
@@ -104,6 +111,13 @@ void ModDownloader::FetchModsListFromAPI()
 				for (auto& attribute : versions.GetArray())
 				{
 					assert(attribute.IsObject());
+					// Format testing
+					if (!attribute.HasMember("Version") || !attribute.HasMember("Checksum"))
+					{
+						spdlog::warn("Verified mods manifesto format is unrecognized, skipping loading.");
+						return;
+					}
+
 					std::string version = attribute["Version"].GetString();
 					std::string checksum = attribute["Checksum"].GetString();
 					modVersions.insert({version, {.checksum = checksum}});