Fixed multiple LINQ using shared resources and cause crashes

Added an null check in AIObjectiveManager.cs to avoid accessing removed resources
Use shuffledGaps instead of gapList to ensure update order requirement(already in master)
Updated parallelism count

Barotrauma/BarotraumaShared/SharedSource/Characters/AI/HumanAIController.cs

@@ -382,8 +382,13 @@ namespace Barotrauma
             }
             steeringBuffer = Math.Clamp(steeringBuffer, minSteeringBuffer, maxSteeringBuffer);
 
-            AnimController.Crouching = shouldCrouch;
-            CheckCrouching(deltaTime);
+            // in case of somehow AnimController was a null, eg. something removed AnimController in the middle of an update
+            if (AnimController != null) 
+            {
+                AnimController.Crouching = shouldCrouch;
+                CheckCrouching(deltaTime);
+            }
+
             Character.ClearInputs();
             
             if (SortTimer > 0.0f)
@@ -1638,7 +1643,8 @@ namespace Barotrauma
             if (mode == AIObjectiveCombat.CombatMode.None) { return; }
             if (Character.IsDead || Character.IsIncapacitated || Character.Removed) { return; }
             if (!Character.IsBot) { return; }
-            if (ObjectiveManager.Objectives.FirstOrDefault(o => o is AIObjectiveCombat) is AIObjectiveCombat combatObjective)
+            List<AIObjective> ObjectivesLocal = ObjectiveManager.Objectives;
+            if (ObjectivesLocal.FirstOrDefault(o => o is AIObjectiveCombat) is AIObjectiveCombat combatObjective)
             {
                 // Don't replace offensive mode with something else
                 if (combatObjective.Mode == AIObjectiveCombat.CombatMode.Offensive && mode != AIObjectiveCombat.CombatMode.Offensive) { return; }

Barotrauma/BarotraumaShared/SharedSource/Characters/AI/Objectives/AIObjectiveManager.cs

@@ -126,7 +126,7 @@ namespace Barotrauma
             }
             else
             {
-                Objectives.RemoveAll(o => o.GetType() == type);
+                Objectives.RemoveAll(o => o?.GetType() == type);
             }
             Objectives.Add(objective);
         }