2 | sector must be fort with eff>5%, mil>5, gun>0, shell>0
18 | at sector that doesn't exist
20 | at ship that doesn't exist
22 | at valid target, but with insufficient mil
35 || fort firing nowhere (shell consumed)
39 | at ship out of range
41 | at sub, server pretends out of range
46 || fort firing at bogus target
48 | at sea, fractional range, ~50% chance
58 || fort firing at undefended target
59 | 5% fort with one gun
60 | 100% fort with one gun
61 | 100% fort with plenty of guns
62 | at own empty highway
67 | firing at bridges is covered in bridgefall-test
69 | at harbor with stuff
77 | at cs at sea, one sunk
82 | at cs in port, one sunk