Micro AIs: fix errors caused when WML events interfere with AI actions

If a WML event takes a unit off the map, many of the AIs would
previously have run into problems by trying to access a unit that is
then not there any more.  Thus, the existence of the unit needs to be
verified before continuing in cases when this would cause errors.

data/ai/micro_ais/cas/ca_big_animals.lua

@@ -83,8 +83,10 @@ function ca_big_animals:execution(ai, cfg)
 
         if (best_hex[1] ~= unit.x) or (best_hex[2] ~= unit.y) then
             AH.checked_move(ai, unit, best_hex[1], best_hex[2])  -- partial move only
+            if (not unit) or (not unit.valid) then return end
         else  -- If animal did not move, we need to stop it (also delete the goal)
             AH.checked_stopunit_moves(ai, unit)
+            if (not unit) or (not unit.valid) then return end
             unit.variables.goal_x = nil
             unit.variables.goal_y = nil
         end
@@ -108,7 +110,6 @@ function ca_big_animals:execution(ai, cfg)
         if target.id then
             AH.checked_attack(ai, unit, target)
         end
-
     end
 end
 

data/ai/micro_ais/cas/ca_bottleneck_move.lua

@@ -499,6 +499,7 @@ function ca_bottleneck_move:execution(ai, cfg, self)
         if (self.data.unit.x ~= self.data.hex[1]) or (self.data.unit.y ~= self.data.hex[2]) then  -- test needed for level-up move
             AH.checked_move(ai, self.data.unit, self.data.hex[1], self.data.hex[2])   -- don't want full move, as this might be stepping out of the way
         end
+        if (not self.data.unit) or (not self.data.unit.valid) then return end
 
         -- If this is a move for a level-up attack, do the attack also
         if self.data.lu_defender then

data/ai/micro_ais/cas/ca_coward.lua

@@ -116,10 +116,9 @@ function ca_coward:execution(ai, cfg)
     if (mx ~= unit.x or my ~= unit.y) then
         AH.movefull_stopunit(ai, unit, mx, my)
     end
+    if (not unit) or (not unit.valid) then return end
 
-    -- Get unit again, just in case it was killed by a moveto event
-    local unit = wesnoth.get_units{ id = cfg.id }[1]
-    if unit then AH.checked_stopunit_all(ai, unit) end
+    AH.checked_stopunit_all(ai, unit)
 end
 
 return ca_coward

data/ai/micro_ais/cas/ca_forest_animals_move.lua

@@ -122,9 +122,14 @@ function ca_forest_animals_move:execution(ai, cfg)
 
         -- Now we check for close enemies again, as we might just have moved within reach of some
         local close_enemies = {}
-        for j,e in ipairs(enemies) do
-            if (H.distance_between(unit.x, unit.y, e.x, e.y) <= unit.max_moves+1) then
-                table.insert(close_enemies, e)
+
+        -- We use a trick here to exclude the case when the unit might have been
+        -- removed in an event above
+        if unit and unit.valid then
+            for j,e in ipairs(enemies) do
+                if (H.distance_between(unit.x, unit.y, e.x, e.y) <= unit.max_moves+1) then
+                    table.insert(close_enemies, e)
+                end
             end
         end
         --print('  #close_enemies after move', #close_enemies, #enemies, unit.id)
@@ -163,7 +168,6 @@ function ca_forest_animals_move:execution(ai, cfg)
         -- Finally, take moves away, as only partial move might have been done
         -- Also attacks, as these units never attack
         if unit and unit.valid then AH.checked_stopunit_all(ai, unit) end
-        -- Need this ^ test here because bunnies might have disappeared
     end
 end
 

data/ai/micro_ais/cas/ca_forest_animals_tusker_attack.lua

@@ -55,6 +55,8 @@ function ca_forest_animals_tusker_attack:execution(ai, cfg)
     end)
     --print('attacker', attacker.x, attacker.y, ' -> ', best_hex[1], best_hex[2])
     AH.movefull_stopunit(ai, attacker, best_hex)
+    if (not attacker) or (not attacker.valid) then return end
+    if (not target) or (not target.valid) then return end
 
     -- If adjacent, attack
     local dist = H.distance_between(attacker.x, attacker.y, target.x, target.y)

data/ai/micro_ais/cas/ca_forest_animals_tusklet_move.lua

@@ -41,7 +41,7 @@ function ca_forest_animals_tusklet_move:execution(ai, cfg)
         AH.movefull_stopunit(ai, tusklet, best_hex)
 
         -- Also make sure tusklets never attack
-        AH.checked_stopunit_all(ai, tusklet)
+        if tusklet and tusklet.valid then AH.checked_stopunit_all(ai, tusklet) end
     end
 end
 

data/ai/micro_ais/cas/ca_goto.lua

@@ -206,6 +206,7 @@ function ca_goto:execution(ai, cfg, self)
     else
         AH.checked_stopunit_moves(ai, best_unit)
     end
+    if (not best_unit) or (not best_unit.valid) then return end
 
     -- If release_unit_at_goal= or release_all_units_at_goal= key is set:
     -- Check if the unit made it to one of the goal hexes

data/ai/micro_ais/cas/ca_hang_out.lua

@@ -128,12 +128,12 @@ function ca_hang_out:execution(ai, cfg, self)
         for i,u in ipairs(units) do
             AH.checked_stopunit_moves(ai, u)
             -- Also remove the markers
-            u.variables.mai_hangout_moved = nil
+            if u and u.valid then u.variables.mai_hangout_moved = nil end
         end
     else
         -- Otherwise move unit and mark as having been used
         AH.checked_move(ai, best_unit, best_hex[1], best_hex[2])
-        best_unit.variables.mai_hangout_moved = true
+        if best_unit and best_unit.valid then best_unit.variables.mai_hangout_moved = true end
     end
 end
 

data/ai/micro_ais/cas/ca_hunter.lua

@@ -114,8 +114,10 @@ function ca_hunter:execution(ai, cfg)
 
         if (best_hex[1] ~= unit.x) or (best_hex[2] ~= unit.y) then
             AH.checked_move(ai, unit, best_hex[1], best_hex[2])  -- partial move only
+            if (not unit) or (not unit.valid) then return end
         else  -- If hunter did not move, we need to stop it (also delete the goal)
             AH.checked_stopunit_moves(ai, unit)
+            if (not unit) or (not unit.valid) then return end
             unit.variables.goal_x, unit.variables.goal_y = nil, nil
         end
 
@@ -149,6 +151,7 @@ function ca_hunter:execution(ai, cfg)
         if next_hop then
             --print(next_hop[1], next_hop[2])
             AH.movefull_stopunit(ai, unit, next_hop)
+            if (not unit) or (not unit.valid) then return end
 
             -- If there's an enemy on the 'home' hex and we got right next to it, attack that enemy
             if (H.distance_between(cfg.home_x, cfg.home_y, next_hop[1], next_hop[2]) == 1) then
@@ -158,15 +161,17 @@ function ca_hunter:execution(ai, cfg)
                         W.message { speaker = unit.id, message = 'Get out of my home!' }
                     end
                     AH.checked_attack(ai, unit, enemy)
+                    if (not unit) or (not unit.valid) then return end
                 end
             end
         end
 
         -- We also attack the weakest adjacent enemy, if still possible
         hunter_attack_weakest_adj_enemy(ai, unit)
+        if (not unit) or (not unit.valid) then return end
 
         -- If the unit got home, start the resting counter
-        if unit.valid and (unit.x == cfg.home_x) and (unit.y == cfg.home_y) then
+        if (unit.x == cfg.home_x) and (unit.y == cfg.home_y) then
             unit.variables.hunting_status = 'resting'
             unit.variables.resting_until = wesnoth.current.turn + (cfg.rest_turns or 3)
             if cfg.show_messages then
@@ -182,12 +187,14 @@ function ca_hunter:execution(ai, cfg)
     if (unit.variables.hunting_status == 'resting') then
         -- So all we need to do is take moves away from the unit
         AH.checked_stopunit_moves(ai, unit)
+        if (not unit) or (not unit.valid) then return end
 
         -- However, we do also attack the weakest adjacent enemy, if still possible
         hunter_attack_weakest_adj_enemy(ai, unit)
+        if (not unit) or (not unit.valid) then return end
 
         -- If this is the last turn of resting, we also remove the status and turn variable
-        if unit.valid and (unit.hitpoints >= unit.max_hitpoints) and (unit.variables.resting_until <= wesnoth.current.turn) then
+        if (unit.hitpoints >= unit.max_hitpoints) and (unit.variables.resting_until <= wesnoth.current.turn) then
             unit.variables.hunting_status = nil
             unit.variables.resting_until = nil
             if cfg.show_messages then

data/ai/micro_ais/cas/ca_lurkers.lua

@@ -63,11 +63,13 @@ function ca_lurkers:execution(ai, cfg)
             local rand = math.random(1, rattack_nt_target:size())
             local dst = rattack_nt_target:to_stable_pairs()
             AH.movefull_stopunit(ai, me, dst[rand])
+            if (not me) or (not me.valid) then return end
             AH.checked_attack(ai, me, target)
             attacked = true
             break
        end
     end
+    if (not me) or (not me.valid) then return end
 
     -- If unit has moves left (that is, it didn't attack), go to random wander terrain hex
     -- Check first that unit wasn't killed in the attack
@@ -91,9 +93,10 @@ function ca_lurkers:execution(ai, cfg)
         end
         AH.movefull_stopunit(ai, me, dst)
     end
+    if (not me) or (not me.valid) then return end
 
     -- If the unit has moves or attacks left at this point, take them away
-    if me and me.valid then AH.checked_stopunit_all(ai, me) end
+    AH.checked_stopunit_all(ai, me)
 end
 
 return ca_lurkers

data/ai/micro_ais/cas/ca_messenger_attack.lua

@@ -156,6 +156,9 @@ function ca_messenger_attack:execution(ai, cfg, self)
     local defender = wesnoth.get_unit(self.data.best_attack.target.x, self.data.best_attack.target.y)
 
     AH.movefull_stopunit(ai, attacker, self.data.best_attack.dst.x, self.data.best_attack.dst.y)
+    if (not attacker) or (not attacker.valid) then return end
+    if (not defender) or (not defender.valid) then return end
+
     AH.checked_attack(ai, attacker, defender)
     self.data.best_attack = nil
 end

data/ai/micro_ais/cas/ca_messenger_move.lua

@@ -62,6 +62,7 @@ function ca_messenger_move:execution(ai, cfg, self)
     else
         AH.checked_stopunit_moves(ai, messenger)
     end
+    if (not messenger) or (not messenger.valid) then return end
 
     -- We also test whether an attack without retaliation or with little damage is possible
     if (not H.get_child(messenger.__cfg, 'attack')) then return end
@@ -116,6 +117,7 @@ function ca_messenger_move:execution(ai, cfg, self)
             AH.checked_attack(ai, messenger, target)
         end
     end
+    if (not messenger) or (not messenger.valid) then return end
 
     -- Finally, make sure unit is really done after this
     AH.checked_stopunit_attacks(ai, messenger)

data/ai/micro_ais/cas/ca_patrol.lua

@@ -124,6 +124,7 @@ function ca_patrol:execution(ai, cfg, self)
                 AH.checked_stopunit_moves(ai, patrol)
             end
         end
+        if (not patrol) or (not patrol.valid) then return end
     end
 
     -- Attack unit on the last waypoint under all circumstances if cfg.one_time_only is set
@@ -152,9 +153,9 @@ function ca_patrol:execution(ai, cfg, self)
             break
         end
     end
+    if (not patrol) or (not patrol.valid) then return end
 
-    -- Check that patrol is not killed
-    if patrol and patrol.valid then AH.checked_stopunit_all(ai, patrol) end
+    AH.checked_stopunit_all(ai, patrol)
 end
 
 return ca_patrol

data/ai/micro_ais/cas/ca_protect_unit_attack.lua

@@ -127,6 +127,9 @@ function ca_protect_unit_attack:execution(ai, cfg, self)
     local defender = wesnoth.get_unit(self.data.best_attack.target.x, self.data.best_attack.target.y)
 
     AH.movefull_stopunit(ai, attacker, self.data.best_attack.dst.x, self.data.best_attack.dst.y)
+    if (not attacker) or (not attacker.valid) then return end
+    if (not defender) or (not defender.valid) then return end
+
     AH.checked_attack(ai, attacker, defender)
     self.data.best_attack = nil
 end

data/ai/micro_ais/cas/ca_simple_attack.lua

@@ -79,6 +79,9 @@ function ca_simple_attack:execution(ai, cfg, self)
     local defender = wesnoth.get_unit(self.data.attack.target.x, self.data.attack.target.y)
 
     AH.movefull_outofway_stopunit(ai, attacker, self.data.attack.dst.x, self.data.attack.dst.y)
+    if (not attacker) or (not attacker.valid) then return end
+    if (not defender) or (not defender.valid) then return end
+
     AH.checked_attack(ai, attacker, defender, (cfg.weapon or -1))
     self.data.attack = nil
 end

data/ai/micro_ais/cas/ca_stationed_guardian.lua

@@ -92,8 +92,8 @@ function ca_stationed_guardian:execution(ai, cfg)
         if (best_defense ~= -9e99) then
             --print("Attack at:",attack_loc[1],attack_loc[2],best_defense)
             AH.movefull_stopunit(ai, unit, attack_loc)
-            -- There should be an ai.check_attack_action() here in case something weird is
-            -- done in a 'moveto' event.
+            if (not unit) or (not unit.valid) then return end
+            if (not target) or (not target.valid) then return end
             AH.checked_attack(ai, unit, target)
         else  -- otherwise move toward that enemy
             --print("Cannot reach target, moving toward it")
@@ -125,9 +125,9 @@ function ca_stationed_guardian:execution(ai, cfg)
         AH.movefull_stopunit(ai, unit, nh)
     end
 
-    -- Get unit again, just in case something was done to it in a 'moveto' or 'attack' event
-    local unit = wesnoth.get_units{ id = cfg.id }[1]
-    if unit then AH.checked_stopunit_moves(ai, unit) end
+    if (not unit) or (not unit.valid) then return end
+
+    AH.checked_stopunit_moves(ai, unit)
     -- If there are attacks left and unit ended up next to an enemy, we'll leave this to RCA AI
 end
 

data/ai/micro_ais/cas/ca_wolves_multipacks_attack.lua

@@ -182,7 +182,7 @@ function ca_wolves_multipacks_attack:execution(ai, cfg)
                         W.label { x = w.x, y = w.y, text = "" }
                     end
                     AH.movefull_stopunit(ai, w, best_hex)
-                    if cfg.show_pack_number then
+                    if cfg.show_pack_number and w and w.valid then
                         WMPF.color_label(w.x, w.y, pack_number)
                     end
                 end

data/ai/micro_ais/cas/ca_wolves_multipacks_wander.lua

@@ -132,7 +132,7 @@ function ca_wolves_multipacks_wander:execution(ai, cfg)
                 W.label { x = w.x, y = w.y, text = "" }
             end
             AH.movefull_stopunit(ai, w, best_hex)
-            if cfg.show_pack_number then
+            if cfg.show_pack_number and w and w.valid then
                 WMPF.color_label(w.x, w.y, k)
             end
         end

data/ai/micro_ais/cas/ca_zone_guardian.lua

@@ -84,6 +84,7 @@ function ca_zone_guardian:execution(ai, cfg)
             if (best_defense ~= -9e99) then
                 --print("Attack at:",attack_loc[1],attack_loc[2],best_defense)
                 AH.movefull_stopunit(ai, unit, attack_loc)
+                if (not unit) or (not unit.valid) then return end
                 AH.checked_attack(ai, unit, target)
             else  -- otherwise move toward that enemy
                 --print("Cannot reach target, moving toward it")
@@ -153,10 +154,9 @@ function ca_zone_guardian:execution(ai, cfg)
             AH.movefull_stopunit(ai, unit, nh)
         end
     end
+    if (not unit) or (not unit.valid) then return end
 
-    -- Get unit again, just in case something was done to it in a 'moveto' or 'attack' event
-    local unit = wesnoth.get_units{ id = cfg.id }[1]
-    if unit then AH.checked_stopunit_moves(ai, unit) end
+    AH.checked_stopunit_moves(ai, unit)
     -- If there are attacks left and unit ended up next to an enemy, we'll leave this to RCA AI
 end