How to apply custom validation in vue-tel-input

Question

As the title says, what is the process to applying a customValidate regex in vue-tel-input? You can see customValidate as the last item in the list of props. I have a standard setup like in this code sandbox. However, when I add a regex for the phone number to only allow a phone number with digits and a starting "+", the code hangs and kills my browser, customValidate: /^\+\d+$/. Is my formatting correct or is there another approach I should take? Is my regex ok?