Issue with entering value into By Count (in adding a plan)

[jcroy]

Describe the bug
If you're setting up a new plan and trying to enter a count value for retention policy and clear out the values it automatically hides the text input box when it equals 0. Thus requiring you to have to re-click "By Count" again to renter text.

So if you are trying to put in a smaller number such as 10, I'll put in 110 and delete the leading 1 to prevent the text box from going away. You could technically avoid this by using the up/down arrows.

To Reproduce
Steps to reproduce the behavior:

1. Go to add a plan.
2. Navigate to By Count.
3. Clear out the default value of 30.
4. Text input box disappears.
5. Re-click By Count.
6. Box reappears with default value of 30.

Expected behavior
Not hiding text box if value becomes 0. While I understand desired goal it makes it difficult to enter a custom value.

Platform Info

Docker container using docker compose from backrest github.