Fix bug in percentage field reset(issues#121)

[Autumn-Rains-yan]

Describe the bug
After i filled in a default value of percent field, i couldn't get it back to "empty" state, it always showed a "0" in the input box

To Reproduce
Steps to reproduce the behavior:

Create a field and type is Percent
filled a "5" into the input box of Default value in the field setting modal, and then click the button "OK"
double-click the field name for reopenning the field setting modal, empty the input box of Default value, and then click the button "OK"
double-click the field name again, you will see "0" in the input box of Default value
Expected behavior
Leave it empty when I remove all content from the input box.

Desktop (please complete the following information):

OS: Windows 10
Browser Chrome
Version 108.0.5359.125

[CLAassistant]

All committers have signed the CLA.

[Sky-FE]

Hi, @Autumn-Rains-yan.
You have found the error position, but the PR will cause the "0" to not be filled.
I think we should fix it like this: #215.
Thank you for your interest in APITable. If you've got any questions, just let me know when you feel free.