Defensive programming for Party

Signed-off-by: Deukhoofd <Deukhoofd@gmail.com>

src/Battling/Models/CreatureParty.hpp

@@ -24,6 +24,9 @@ namespace CreatureLib::Battling {
         void Switch(size_t a, size_t b) noexcept { _party.Swap(a, b); }
 
         Creature* SwapInto(size_t index, Creature* creature) {
+            if (index >= _party.Count()) {
+                THROW("Index was out of bounds for party.")
+            }
             auto p = _party.TakeOwnership(index);
             _party.Set(index, creature);
             return p;