npm and error messages

node_modules/core-js/modules/es6.object.to-string.js

@@ -0,0 +1,10 @@
+'use strict';
+// 19.1.3.6 Object.prototype.toString()
+var classof = require('./_classof');
+var test = {};
+test[require('./_wks')('toStringTag')] = 'z';
+if (test + '' != '[object z]') {
+  require('./_redefine')(Object.prototype, 'toString', function toString() {
+    return '[object ' + classof(this) + ']';
+  }, true);
+}