npm and error messages

node_modules/es5-ext/object/validate-stringifiable.js

@@ -0,0 +1,12 @@
+"use strict";
+
+var isCallable = require("./is-callable");
+
+module.exports = function (stringifiable) {
+	try {
+		if (stringifiable && isCallable(stringifiable.toString)) return stringifiable.toString();
+		return String(stringifiable);
+	} catch (e) {
+		throw new TypeError("Passed argument cannot be stringifed");
+	}
+};