npm and error messages

node_modules/core-js/modules/_ctx.js

@@ -0,0 +1,20 @@
+// optional / simple context binding
+var aFunction = require('./_a-function');
+module.exports = function (fn, that, length) {
+  aFunction(fn);
+  if (that === undefined) return fn;
+  switch (length) {
+    case 1: return function (a) {
+      return fn.call(that, a);
+    };
+    case 2: return function (a, b) {
+      return fn.call(that, a, b);
+    };
+    case 3: return function (a, b, c) {
+      return fn.call(that, a, b, c);
+    };
+  }
+  return function (/* ...args */) {
+    return fn.apply(that, arguments);
+  };
+};