reCaptcha is throwing exception

Hi, I have implemented reCaptcha V2 in the form by using the following tag@div class=@g-recaptcha@ data-callback=@verifyCaptcha@ data-sitekey=@####@ data-type=@audio@@;@/div@ and registering the Captcha API using @script src=@https://www.google.com/recaptcha/api.js@ async=@async@ defer=@defer@@@/script@ in the header section. I am not using Kentico out-of-box reCapcga control. But while I am submitting the form, not sure why it is hitting the GetCaptachaValue() method inside TextCaptcha.ascx.cs file. And since there is no null check of textBoxList it is throwing error. Could anyone please let me know why it is hitting that function?Thanks, Joy