[Auth UI] Email field fills up with phone number after back from verification page

[keithtkl]

When back from verification page and then switch from phone number to use email instead, can see the phone number input is filled on the email field

• Skygear Server Date/Version: Not sure
• Application Platform: Tested on Rees

Expected Results

Email field should be cleared as the previous inputted phone number is not valid now

Actual Results

Email field is filled with phone number

Steps to reproduce

1. Open signup / login page
2. Try use phone number to proceed
3. On the verification page, back to the previous step, and select email this time instead
4. See the previous inputted phone number shown on the email field