Fix multiple target acquisition, and crash after destruction

ships/pirate.gd

@@ -18,15 +18,22 @@ var direction_tolerance_rad: float:
     get:
         return deg_to_rad(direction_tolerance_deg)
 
-func _find_a_target():
+func _acquire_closest_target() -> void:
     var ships := get_tree().get_nodes_in_group("ships")
     ships.erase(self)
-    return ships[0] if ships.size() > 0 else null
+
+    var closest_ship: Ship = null
+    var closest_distance := self.detection_range
+
+    for ship in ships:
+        var distance := global_transform.origin.distance_to(ship.global_transform.origin)
+        if distance < closest_distance:
+            closest_distance = distance
+            closest_ship = ship
+
+    self.set_target(closest_ship)
 
 func _physics_process(delta: float):
-    if self.target == null:
-        self.set_target(_find_a_target())
-
     if self.target == null:
         self.current_state = State.IDLE
 
@@ -49,10 +56,8 @@ func _pointing_in_direction(direction: Vector3) -> bool:
     return current_direction.angle_to(direction) <= direction_tolerance_rad
 
 func idle_behavior(_delta: float):
-    if self.target == null:
-        return
-
-    if player_in_range():
+    self._acquire_closest_target()
+    if self.target != null:
         current_state = State.PURSUE
 
 func pursue_behavior(_delta: float):
@@ -83,11 +88,10 @@ func retreat_behavior(_delta: float):
     if distance >= preferred_distance:
         current_state = State.ATTACK
 
-func player_in_range() -> bool:
-    var distance := global_transform.origin.distance_to(self.target.global_transform.origin)
-    return distance <= detection_range
-
 func _integrate_forces(state: PhysicsDirectBodyState3D) -> void:
+    if self.target == null:
+        self.current_state = State.IDLE
+
     if self.current_state == State.IDLE:
         return