build: fix warnings due to empty switch statememts if no language support is built (#1015)

src/lib/data/indexer/interprocess/shared_types/SharedIndexerCommand.cpp

@@ -71,6 +71,7 @@ std::shared_ptr<IndexerCommand> SharedIndexerCommand::fromShared(const SharedInd
 			indexerCommand.getSourceFilePath().wstr() + L". The type is unknown.");
 		break;
 #endif	  // BUILD_PYTHON_LANGUAGE_PACKAGE
+	case UNKNOWN:
 	default:
 		LOG_ERROR(
 			L"Cannot convert shared IndexerCommand for file: " +

src/lib/settings/ProjectSettings.cpp

@@ -476,7 +476,7 @@ SettingsMigrator ProjectSettings::getMigrations() const
 		case LANGUAGE_PYTHON:
 			continue;
 #endif	  // BUILD_PYTHON_LANGUAGE_PACKAGE
-
+		case SOURCE_GROUP_CUSTOM_COMMAND:
 		default:
 			continue;
 		}

src/lib_gui/qt/window/QtStartScreen.cpp

@@ -134,6 +134,7 @@ void QtStartScreen::updateButtons()
 				button->setIcon(m_pythonIcon);
 				break;
 #endif	  // BUILD_PYTHON_LANGUAGE_PACKAGE
+			case LANGUAGE_CUSTOM:
 			default:
 				button->setIcon(m_projectIcon);
 				break;