(gdb) bt
#0  raise (sig=<optimized out>) at ../sysdeps/unix/sysv/linux/raise.c:49
#1  0x00005555558a1366 in fc_assert_fail (file=0x55555594da46 "../../src/common/actions.c", 
    function=0x555555950488 <__FUNCTION__.20> "action_prob", line=3807, 
    assertion=0x55555594ee30 "(action_prob_is_signal(chance) || chance.max <= 200)", 
    message=0x555555987575 "nologmsg:%s") at ../../src/utility/log.c:570
#2  0x0000555555756f1a in action_prob (wanted_action=5, actor_player=0x555556ba52d0, 
    actor_city=0x555555e7cab0, actor_building=0x0, actor_tile=0x5555577e7d40, actor_unit=0x55555604d5c0, 
    actor_unittype_p=0x0, actor_output=0x0, actor_specialist=0x0, actor_home=0x55555619ad40, 
    target_player=0x555556ba52d0, target_city=0x555555e7cab0, target_building=0x0, 
    target_tile=0x5555577e7d40, target_unit=0x0, target_unittype_p=0x555555c86dc8 <unit_types+59368>, 
    target_output=0x0, target_specialist=0x0) at ../../src/common/actions.c:3807
#3  0x00005555557572df in action_prob_vs_city_full (actor_unit=0x55555604d5c0, actor_home=0x55555619ad40, 
    actor_tile=0x5555577e7d40, act_id=5, target_city=0x555555e7cab0) at ../../src/common/actions.c:3899
#4  0x0000555555757334 in action_prob_vs_city (actor_unit=0x55555604d5c0, act_id=5, 
    target_city=0x555555e7cab0) at ../../src/common/actions.c:3916
#5  0x00005555555fcb67 in may_unit_act_vs_city (actor=0x55555604d5c0, target=0x555555e7cab0, 
    accept_all_actions=false) at ../../src/server/actiontools.c:589
#6  0x00005555555fcbd2 in action_tgt_city (actor=0x55555604d5c0, target_tile=0x5555577e7d40, 
    accept_all_actions=false) at ../../src/server/actiontools.c:613
#7  0x00005555555cb625 in unit_move (punit=0x55555604d5c0, pdesttile=0x5555577e7d40, move_cost=9, 
    embark_to=0x0, conquer_city_allowed=false) at ../../src/server/unittools.c:3664
#8  0x00005555555c1d2e in teleport_unit_to_city (punit=0x55555604d5c0, pcity=0x555555e7cab0, move_cost=9, 
    verbose=false) at ../../src/server/unittools.c:1166
#9  0x00005555556ddebd in diplomat_escape_full (pplayer=0x555556ba52d0, pdiplomat=0x55555604d5c0, 
    city_related=true, ptile=0x5555577e9b40, 
    vlink=0x555555ad52c0 <buf> "[l tgt=\"city\" id=209 name=\"Thessalonica\" /]", paction=0x555555d78510)
    at ../../src/server/diplomats.c:1954
#10 0x00005555556ddcec in diplomat_escape (pplayer=0x555556ba52d0, pdiplomat=0x55555604d5c0, 
    pcity=0x55555650b740, paction=0x555555d78510) at ../../src/server/diplomats.c:1900
#11 0x00005555556dbc85 in diplomat_sabotage (pplayer=0x555556ba52d0, pdiplomat=0x55555604d5c0, 
    pcity=0x55555650b740, improvement=200, paction=0x555555d78510) at ../../src/server/diplomats.c:1218
#12 0x00005555556c362e in unit_perform_action (pplayer=0x555556ba52d0, actor_id=30528, target_id=15142, 
    sub_tgt_id=0, name=0x55555594c3cd "", action_type=9, requester=ACT_REQ_PLAYER)
    at ../../src/server/unithand.c:2894
#13 0x00005555556c2e5e in handle_unit_do_action (pplayer=0x555556ba52d0, actor_id=30528, target_id=15142, 
    sub_tgt_id=0, name=0x55555594c3cd "", action_type=9) at ../../src/server/unithand.c:2697
#14 0x0000555555745ea4 in dai_diplomat_city (ait=0x555555abd4a0 <ai_types>, punit=0x55555604d5c0, 
    ctarget=0x55555650b740) at ../../../src/ai/default/aidiplomat.c:389
#15 0x0000555555747f0b in dai_manage_diplomat (ait=0x555555abd4a0 <ai_types>, pplayer=0x555556ba52d0, 
    punit=0x55555604d5c0) at ../../../src/ai/default/aidiplomat.c:862
#16 0x000055555572ebc2 in dai_manage_unit (ait=0x555555abd4a0 <ai_types>, pplayer=0x555556ba52d0, 
    punit=0x55555604d5c0) at ../../../src/ai/default/aiunit.c:2647
#17 0x000055555572f9d3 in dai_manage_units (ait=0x555555abd4a0 <ai_types>, pplayer=0x555556ba52d0)
    at ../../../src/ai/default/aiunit.c:2837
#18 0x00005555557183ac in dai_do_first_activities (ait=0x555555abd4a0 <ai_types>, pplayer=0x555556ba52d0)
    at ../../../src/ai/default/aihand.c:746
#19 0x00005555556cd26c in cai_do_first_activities (pplayer=0x555556ba52d0)
    at ../../../src/ai/classic/classicai.c:448
#20 0x000055555559ad7a in ai_start_phase () at ../../src/server/srv_main.c:1094
#21 0x000055555559be46 in begin_phase (is_new_phase=true) at ../../src/server/srv_main.c:1288
#22 0x00005555555a1578 in srv_running () at ../../src/server/srv_main.c:2754
#23 0x00005555555a34f2 in srv_main () at ../../src/server/srv_main.c:3403
#24 0x0000555555593409 in main (argc=6, argv=0x7fffffffe108) at ../../src/server/civserver.c:481