npm and error messages

node_modules/clean-css/lib/utils/clone-array.js

@@ -0,0 +1,12 @@
+function cloneArray(array) {
+  var cloned = array.slice(0);
+
+  for (var i = 0, l = cloned.length; i < l; i++) {
+    if (Array.isArray(cloned[i]))
+      cloned[i] = cloneArray(cloned[i]);
+  }
+
+  return cloned;
+}
+
+module.exports = cloneArray;