[Freeciv-Dev] (PR#14618) Continent-range Effects Crash

["Benedict Adamson" <badamson@xxxxxxxxxxx>]

<URL: http://bugs.freeciv.org/Ticket/Display.html?id=14618 >

Using SVN HEAD with a rule-set (Ancients) that has a continent-range 
effect, the requirements code crashes with a SEGV at requirements.c:594 
because target_city is NULL.

The troublesome effect seems to be this:

[effect_great_wall]
name    = "Defend_Bonus"
value   = 200
reqs    =
     { "type", "name", "range"
       "Building", "Great Wall", "Continent"
       "UnitClass", "Land", "Local"
     }

(