Added error handler to web server.

src/errors.js

@@ -0,0 +1,20 @@
+'use strict';
+
+class HttpError extends Error {
+	constructor(message, httpCode, friendlyMessage, data) {
+		super(message);
+
+		this.name = 'HttpError';
+		this.httpCode = httpCode;
+
+		if (friendlyMessage) {
+			this.friendlyMessage = friendlyMessage;
+		}
+
+		if (data) {
+			this.data = data;
+		}
+	}
+}
+
+module.exports = { HttpError };