modified

build/node_modules/webpack/lib/ConcurrentCompilationError.js

@@ -0,0 +1,18 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Maksim Nazarjev @acupofspirt
+*/
+
+"use strict";
+
+const WebpackError = require("./WebpackError");
+
+module.exports = class ConcurrentCompilationError extends WebpackError {
+	constructor() {
+		super();
+
+		this.name = "ConcurrentCompilationError";
+		this.message =
+			"You ran Webpack twice. Each instance only supports a single concurrent compilation at a time.";
+	}
+};