knockout.js Uncaught TypeError: Unable to process binding
<p>I am using Porto v2.2.0 – Ultimate Responsive Magento Theme and showing error like </p>

<pre><code>knockout.js:3012 Uncaught TypeError: Unable to process binding "css: function (){return { empty:cart().summary_count == 0} }"
Message: cart is not a function
</code></pre>