Uncaught TypeError: $(...).validate is not a function

When using clientside_valiadtion with webforms a JS error occurs.

Steps to reproduce:
- Create a new webform
- Go to the ‘settings’ tab and select the ‘emails/handlers’ submenu
- Click on the ‘add handler’ button
- An error appears in the Console as follows:
Uncaught TypeError: $(...).validate is not a function