I have enabled phone number validation on one of my fields and it appears to cause a js error for missing ')' (I'm not sure how accurate the actual error is).
Looking at the add page in the setFields function, this is the field with validation enabled (and the complaint in chrome)
["CriticalPhone", [fields.CriticalPhone.visible && fields.CriticalPhone.required ? ew.Validators.required(fields.CriticalPhone.caption) : null, ew.Validators.custom(Phone Number)], fields.CriticalPhone.isInvalid],
This is a similar field without validation:
["RegularPhone", [fields.RegularPhone.visible && fields.RegularPhone.required ? ew.Validators.required(fields.RegularPhone.caption) : null], fields.RegularPhone.isInvalid],
I'm not sure if I'm missing something else in the config or if there is a bug for phone validation.