kingdoms: lua error in determining region owner

src/scripts/kingdoms-run.lua

@@ -38,11 +38,13 @@ function update_owners()
       end
     end
     local u
+    if b ~=nil then
       u = b.units()
       if u~=nil and u.faction~=r.owner then
         r.owner = u.faction
       end
     end
+  end
 end
 
 function process(orders)