Bug, can not get the dns zone list in function app website

[qinrui777]

Describe the bug
Can not get dns zone from function app website

To Reproduce
Steps to reproduce the behavior:

1. Create a new function app with "For Azure cloud "(https://portal.azure.com/#create/Microsoft.Template/uri/https%3A%2F%2Fraw.githubusercontent.com%2Fshibayan%2Fkeyvault-acmebot%2Fmaster%2Fazuredeploy.json) ,get the link from the github repo readm
2. add settings , set "Create new Key vault" to "true"
3. finished step ""Enable App Service Authentication"
4. go to the function app website URL with Chrome https://func-xxxx.azurewebsites.net/add-certificate, See error

Environment (please complete the following information):

• Certificate Type: None
• Certificate Deploy Target: None

Additional context
When I try to revert to commit (Remove default Azure DNS configuration (#248) ), use the template json ,then create another function app, it can work properly.