Fix spawned monster upgrading

[i2amroy]

Fixes #12106 permanently.

This turns the "spawn a new monster" block of 4 lines or so into a single function that takes a monster id and a tripoint and then returns a pointer to the newly made monster. This function updates the summoned monster's last update check to the current date, instead of leaving it at the default value of 0.

[i2amroy]

Anyone know of a better way to do this than searching through the critter_tracker again to find the monster we just added? I couldn't think of any better way to get a permanent pointer to the monster.

[BevapDin]

You could make add_zombie return the new monster, than return add_zombie(...). add_zombie already returns a bool, but is only used in catalua.cpp

But you want to check the result of add_zombie anyway, there are several situations when it wont have add a zombie, calling critter_tracker.mon_at(p) will fail then:

• the monster id was mon_null,
• the monsters location is outside the map
• (most likely) the monster is blacklisted

Edit: I suggest you make the function return the bool from add_zombie directly and let the caller get the monster reference themself, the caller often doesn't need it anyway.

[i2amroy]

Good points, I'll look into them. Thanks. : )