Split initApp in different functions

This makes the function easier to understand and fixes eslint complaints
about the function having too many statements.

app.js

@@ -35,11 +35,36 @@ function initApp(config, callback) {
 	}
 
 	const app = new EventEmitter();
+
 	app.address = null;
 	app.express = express();
 	app.server = http.createServer(app.express);
 	app.webservice = createClient(webserviceUrl);
 
+	loadMiddleware(app);
+
+	// View engine
+	loadViewEngine(app, config);
+
+	// Load routes
+	loadRoutes(app, config);
+
+	// Error handling
+	loadErrorHandling(app, config, callback);
+}
+
+// Get default configurations
+function defaultConfig(config) {
+	if (typeof config.noindex !== 'boolean') {
+		config.noindex = true;
+	}
+	if (typeof config.readonly !== 'boolean') {
+		config.readonly = false;
+	}
+	return config;
+}
+
+function loadMiddleware(app) {
 	// Compression
 	app.express.use(compression());
 
@@ -53,8 +78,9 @@ function initApp(config, callback) {
 	app.express.use(bodyParser.urlencoded({
 		extended: true
 	}));
+}
 
-	// View engine
+function loadViewEngine(app, config) {
 	app.express.engine('html', hbs.express4({
 		extname: '.html',
 		contentHelperName: 'content',
@@ -89,10 +115,16 @@ function initApp(config, callback) {
 		response.locals.host = request.hostname;
 		next();
 	});
+}
 
-	// Load routes
+function loadRoutes(app, config) {
+	// Because there's some overlap between the different routes,
+	//  they have to be loaded in a specific order in order to avoid
+	//  passing mongo the wrong id which would result in
+	//  "ObjectID generation failed." errors (e.g. #277)
 	require('./route/index')(app);
 	require('./route/result/download')(app);
+
 	if (!config.readonly) {
 		require('./route/new')(app);
 		require('./route/task/delete')(app);
@@ -101,12 +133,14 @@ function initApp(config, callback) {
 		require('./route/task/ignore')(app);
 		require('./route/task/unignore')(app);
 	}
+
 	// Needs to be loaded after `/route/new`
 	require('./route/task/index')(app);
 	// Needs to be loaded after `/route/task/edit`
 	require('./route/result/index')(app);
+}
 
-	// Error handling
+function loadErrorHandling(app, config, callback) {
 	app.express.get('*', (request, response) => {
 		response.status(404);
 		response.render('404');
@@ -129,16 +163,4 @@ function initApp(config, callback) {
 		app.address = `http://${address.address}:${address.port}`;
 		callback(error, app);
 	});
-
-}
-
-// Get default configurations
-function defaultConfig(config) {
-	if (typeof config.noindex !== 'boolean') {
-		config.noindex = true;
-	}
-	if (typeof config.readonly !== 'boolean') {
-		config.readonly = false;
-	}
-	return config;
 }