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

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++) {