[Vuejs]-Error in render: "TypeError: Cannot read property 'PAY_TYPE' of null"

You have extra quotation mark on callback_details:

callback_details: {"TXN_ID":"262439","PAY_TYPE":"VISAMASTER","STATUS_INFO":"2003267b9029b3b"}

Try this.

  callback_details: JSON.parse('{"TXN_ID":"262439","PAY_TYPE":"VISAMASTER","STATUS_INFO":"2003267b9029b3b"}'); 

And

<td class="text-xs-left">{{props.item.payment_method}}<br>({{props.item.callback_details.PAY_TYPE}})</td>