[Client] Find closest enchantmentCharge in getItemPtrFromStore()

Enchanted inventory items continuously recharge their enchantment charges, which getItemPtrFromStore() should account for.

Additionally, prevent framelistener errors caused by PlayerItemUse packets about non-existent items.

apps/openmw/mwmp/MechanicsHelper.cpp

@@ -452,17 +452,25 @@ void MechanicsHelper::unequipItemsByEffect(const MWWorld::Ptr& ptr, short enchan
 
 MWWorld::Ptr MechanicsHelper::getItemPtrFromStore(const mwmp::Item& item, MWWorld::ContainerStore& store)
 {
+    MWWorld::Ptr closestPtr;
+
     for (MWWorld::ContainerStoreIterator storeIterator = store.begin(); storeIterator != store.end(); ++storeIterator)
     {
+        // Enchantment charges are often in the process of refilling themselves, so don't check for them here
         if (Misc::StringUtils::ciEqual(item.refId, storeIterator->getCellRef().getRefId()) &&
             item.count == storeIterator->getRefData().getCount() &&
             item.charge == storeIterator->getCellRef().getCharge() &&
-            item.enchantmentCharge == storeIterator->getCellRef().getEnchantmentCharge() &&
             Misc::StringUtils::ciEqual(item.soul, storeIterator->getCellRef().getSoul()))
         {
-            return *storeIterator;
+            // If we have no closestPtr, set it to the Ptr corresponding to this storeIterator; otherwise, make
+            // sure the storeIterator's enchantmentCharge is closer to our goal than that of the previous closestPtr
+            if (!closestPtr || abs(storeIterator->getCellRef().getEnchantmentCharge() - item.enchantmentCharge) <
+                abs(closestPtr.getCellRef().getEnchantmentCharge() - item.enchantmentCharge))
+            {
+                closestPtr = *storeIterator;
+            }
         }
     }
 
-    return 0;
+    return closestPtr;
 }

apps/openmw/mwmp/processors/player/ProcessorPlayerItemUse.hpp

@@ -36,7 +36,11 @@ namespace mwmp
                 MWWorld::InventoryStore &inventoryStore = playerPtr.getClass().getInventoryStore(playerPtr);
 
                 MWWorld::Ptr itemPtr = MechanicsHelper::getItemPtrFromStore(player->usedItem, inventoryStore);
-                MWBase::Environment::get().getWindowManager()->getInventoryWindow()->useItem(itemPtr);
+
+                if (itemPtr)
+                    MWBase::Environment::get().getWindowManager()->getInventoryWindow()->useItem(itemPtr);
+                else
+                    LOG_MESSAGE_SIMPLE(Log::LOG_ERROR, "Cannot use non-existent item %s", player->usedItem.refId.c_str());
             }
         }
     };