docs: addd note

Author: headlessNode

lib/node_modules/@stdlib/ndarray/flatten-by/README.md

@@ -172,6 +172,8 @@ var count = ctx.count;
     -   **indices**: current array element indices.
     -   **arr**: the input [ndarray][@stdlib/ndarray/ctor].
 
+-   The traversal [order][@stdlib/ndarray/orders] of array elements depends on the memory layout of both the input and output ndarrays. As a result, the callback is not guaranteed to receive elements in the view [order][@stdlib/ndarray/orders].
+
 </section>
 
 <!-- /.notes -->

lib/node_modules/@stdlib/ndarray/flatten-by/lib/main.js

@@ -76,6 +76,7 @@ var format = require( '@stdlib/string/format' );
 * // returns [ 2.0, 4.0, 6.0, 8.0, 10.0, 12.0 ]
 */
 function flattenBy( x, options, fcn, thisArg ) {
+	var nargs;
 	var opts;
 	var ctx;
 	var cb;