Several additional checks to ensure battle does not finish turn when ended.

src/Battling/Flow/TurnHandler.cpp

@@ -20,12 +20,15 @@ void TurnHandler::RunTurn(ArbUt::BorrowedPtr<ChoiceQueue> queue) {
 }
 
 void TurnHandler::ExecuteChoice(ArbUt::BorrowedPtr<BaseTurnChoice> choice) {
-    AssertNotNull(choice);
+    AssertNotNull(choice)
     auto choiceKind = choice->GetKind();
     if (choiceKind == TurnChoiceKind::Pass) {
         return;
     }
     auto user = choice->GetUser();
+    AssertNotNull(user)
+    if (user->GetBattle()->HasEnded())
+        return;
     // If the user is fainted, we don't want to execute its choice.
     if (user->IsFainted()) {
         return;
@@ -100,6 +103,8 @@ void TurnHandler::HandleAttackForTarget(ExecutingAttack* attack, const ArbUt::Bo
     auto user = attack->GetUser();
     AssertNotNull(user)
     AssertNotNull(target)
+    if (user->GetBattle()->HasEnded())
+        return;
 
     auto targetSource = target;
     auto userSource = attack;
@@ -130,6 +135,8 @@ void TurnHandler::HandleAttackForTarget(ExecutingAttack* attack, const ArbUt::Bo
     auto& dmgLibrary = library->GetDamageLibrary();
     auto hitIterator = attack->GetTargetIteratorBegin(target.GetRaw());
     for (uint8_t hitIndex = 0; hitIndex < numberOfHits; hitIndex++) {
+        if (user->GetBattle()->HasEnded())
+            return;
         if (user->IsFainted()) {
             break;
         }
@@ -170,7 +177,7 @@ void TurnHandler::HandleAttackForTarget(ExecutingAttack* attack, const ArbUt::Bo
             if (damage > 0) {
                 target->Damage(damage, DamageSource::AttackDamage);
 
-                if (attackData->HasSecondaryEffect()) {
+                if (attackData->HasSecondaryEffect() && !user->IsFainted()) {
                     bool preventSecondary = false;
                     HOOK(PreventSecondaryEffects, targetSource, attack, target.GetRaw(), hitIndex, &preventSecondary);
                     if (!preventSecondary) {

src/Battling/Models/Battle.cpp

@@ -101,6 +101,9 @@ bool Battle::CanSlotBeFilled(uint8_t side, uint8_t index) const {
 }
 
 void Battle::ValidateBattleState() {
+    if (_hasEnded) {
+        return;
+    }
     bool survivingSideExists = false;
     uint8_t winningSide = 255;
     for (uint8_t i = 0; i < _sides.Count(); i++) {