Updated the files.

my-app/node_modules/webpack-sources/lib/helpers/getSource.js

@@ -0,0 +1,17 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+
+"use strict";
+
+const getSource = (sourceMap, index) => {
+	if (index < 0) return null;
+	const { sourceRoot, sources } = sourceMap;
+	const source = sources[index];
+	if (!sourceRoot) return source;
+	if (sourceRoot.endsWith("/")) return sourceRoot + source;
+	return sourceRoot + "/" + source;
+};
+
+module.exports = getSource;