npm and error messages

node_modules/webpack/lib/UseStrictPlugin.js

@@ -0,0 +1,34 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+"use strict";
+
+const ConstDependency = require("./dependencies/ConstDependency");
+
+class UseStrictPlugin {
+	apply(compiler) {
+		compiler.plugin("compilation", (compilation, params) => {
+			params.normalModuleFactory.plugin("parser", (parser) => {
+				const parserInstance = parser;
+				parser.plugin("program", (ast) => {
+					const firstNode = ast.body[0];
+					if(firstNode &&
+						firstNode.type === "ExpressionStatement" &&
+						firstNode.expression.type === "Literal" &&
+						firstNode.expression.value === "use strict") {
+						// Remove "use strict" expression. It will be added later by the renderer again.
+						// This is necessary in order to not break the strict mode when webpack prepends code.
+						// @see https://github.com/webpack/webpack/issues/1970
+						const dep = new ConstDependency("", firstNode.range);
+						dep.loc = firstNode.loc;
+						parserInstance.state.current.addDependency(dep);
+						parserInstance.state.module.strict = true;
+					}
+				});
+			});
+		});
+	}
+}
+
+module.exports = UseStrictPlugin;