Updated the files.

my-app/node_modules/webpack-sources/lib/index.js

@@ -0,0 +1,30 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+
+const defineExport = (name, fn) => {
+	let value;
+	Object.defineProperty(exports, name, {
+		get: () => {
+			if (fn !== undefined) {
+				value = fn();
+				fn = undefined;
+			}
+			return value;
+		},
+		configurable: true
+	});
+};
+
+defineExport("Source", () => require("./Source"));
+
+defineExport("RawSource", () => require("./RawSource"));
+defineExport("OriginalSource", () => require("./OriginalSource"));
+defineExport("SourceMapSource", () => require("./SourceMapSource"));
+defineExport("CachedSource", () => require("./CachedSource"));
+defineExport("ConcatSource", () => require("./ConcatSource"));
+defineExport("ReplaceSource", () => require("./ReplaceSource"));
+defineExport("PrefixSource", () => require("./PrefixSource"));
+defineExport("SizeOnlySource", () => require("./SizeOnlySource"));
+defineExport("CompatSource", () => require("./CompatSource"));