TypeError [ERR_INVALID_ARG_TYPE] webhook when the request type is application/json

Problem

Issue Summary I was using Twilio Studio setting up an appointment reminder, for the confirmation widget, I setup the request and content as below: <img width="345" alt="image" src="https://user-images.githubusercontent.com/499870/95715064-f17bc880-0cb4-11eb-9e80-51ba415e32e5.png"> and my server code is simply like below: [code block] When the confirmation callback hit my server, Twilio webhook throws: [code block] I checked the twilio source code, mainly caused by this function: [code block] obviously if the request type is application/json, express will parse the request.body to an object right away, which causes the issue. By changing the request type to "Form URL Encoded" fixes my issue: <img width="291" alt="image" src="https://user-images.githubusercontent.com/499870/95715350-6b13b680-0cb5-11eb-924a-0cf9e315c0a4.png"> Steps to Reproduce 1. Set up Twilio webhook middleware in your express server 2. Set up a confirmation callback request to your server with request type to application/json Technical details: twilio-node version: twilio@3.49.4 node version: 10.x