Check config before starting MM (#3450)

I think it might be a good idea to check the config at every start.

js/app.js

@@ -117,6 +117,8 @@ function App () {
 			}
 		}
 
+		require(`${global.root_path}/js/check_config.js`);
+
 		try {
 			fs.accessSync(configFilename, fs.F_OK);
 			const c = require(configFilename);

js/check_config.js

@@ -64,12 +64,13 @@ function checkConfigFile () {
 		for (const error of errors) {
 			Log.error(`Line ${error.line} column ${error.column}: ${error.message}`);
 		}
-		return;
+		process.exit(1);
 	}
 
 	Log.info("Checking modules structure configuration... ");
 
 	const position_list = Utils.getModulePositions();
+
 	// Make Ajv schema configuration of modules config
 	// only scan "module" and "position"
 	const schema = {