How can I make a hero independent of a town?

It's not a script, but in
TreeMapProperties
PlayerSpecific
and click around there.
You need to find DieInAWeekWithoutTown
and set it to False for the desired player.
0=1
In this case,

Added 14 minutes later
It will still complain, but it's not a big deal, as it's not a critical error.