Page title doesn't appear as Page Edit headline when title is "0"

[Toutouwai]

Short description of the issue

Expected:

Not expected:

Setup/Environment

• ProcessWire version: 3.0.242

[ryancramerdesign]

I think this is a similar to #1998, as PHP (and thereby ProcessWire) consider "0" to be empty, but this wouldn't be a breaking change for anyone, and seems like a more obvious case that it should use the "0", so I have updated this. Thanks.