npm and error messages

node_modules/webpack/lib/UnsupportedFeatureWarning.js

@@ -0,0 +1,21 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+"use strict";
+
+const WebpackError = require("./WebpackError");
+
+class UnsupportedFeatureWarning extends WebpackError {
+	constructor(module, message) {
+		super();
+
+		this.name = "UnsupportedFeatureWarning";
+		this.message = message;
+		this.origin = this.module = module;
+
+		Error.captureStackTrace(this, this.constructor);
+	}
+}
+
+module.exports = UnsupportedFeatureWarning;