[Fix] Zone state edge case with 0 hp

[Akkadius]

Description

This should potentially fix an issue that I've been unable to reproduce in rarer circumstances where NPC's restore with 0 HP. This change sets HP to max if current HP on restore is 0.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Testing

None

Checklist

• I have performed a self-review of my code. Ensuring variables, functions and methods are named in a human-readable way, comments are added only where naming of variables, functions and methods can't give enough context.
• I have made corresponding changes to the documentation (if applicable, if not delete this line)
• I own the changes of my code and take responsibility for the potential issues that occur