2 | sector must be fort with eff>5%, mil>5, gun>0, shell>0
21 | at sector that doesn't exist
23 | at ship that doesn't exist
27 | at valid target, but with insufficient mil
40 || fort firing nowhere (shell consumed)
44 | at ship out of range
46 | at sub, server pretends out of range
51 || fort firing at bogus target
53 | at sea, fractional range, ~50% chance
63 || fort firing at undefended target
64 | 5% fort with one gun
65 | 100% fort with one gun
66 | 100% fort with plenty of guns
67 | at own empty highway
72 | firing at bridges is covered in bridgefall-test
74 | at harbor with stuff
82 | at cs at sea, one sunk
87 | at cs in port, one sunk