HSM: Template buttons not working smoothly

[akanshaaa19]

Describe the bug
On switching template buttons the behaviour is not smooth.
Also if there is don't add body to the template and just buttons simulator message breaks.

To Reproduce
Steps to reproduce the behavior:

1. Go to HSM create page
2. Add a message
3. Click on 'Add buttons' and select phone number and add phone number
4. Click on URL now
5. The values are still there

Expected behavior
It should work smoothly and values should be updated whenever something is changed

Additional context
Add any other context about the problem here.