Fix/null check set magic equipment and enchantments that cant resolve on a client

Code/client/Games/Forms.cpp

@@ -48,6 +48,12 @@ void TESNPC::Deserialize(const String& acBuffer, uint32_t aChangeFlags) noexcept
     Load(&loadBuffer);
 
     loadBuffer.buffer = nullptr;
+
+    // The spell list loader (TESSpellList::LoadGame) stores whatever the form lookup returns, so spells or
+    // shouts from a mod this client doesn't have (resolved to 0 by our ReadFormId hook) end up as null
+    // entries. Combat AI adds the base NPC's shouts to its inventory without a null check and crashes.
+    if (const uint32_t cRemoved = spellList.RemoveNullEntries())
+        spdlog::warn("NPC {:X}: dropped {} spell/shout entries not found on this client (missing mod?)", formID, cRemoved);
 }
 
 void TESNPC::Initialize() noexcept

Code/client/Games/Skyrim/Actor.cpp

@@ -44,6 +44,8 @@
 #include <ExtraData/ExtraTextDisplayData.h>
 #include <Forms/EnchantmentItem.h>
 #include <Forms/AlchemyItem.h>
+#include <Forms/SpellItem.h>
+#include <Forms/TESShout.h>
 #include <Forms/TESObjectCELL.h>
 
 #include <Structs/Skyrim/AnimationGraphDescriptor_BHR_Master.h>
@@ -701,25 +703,48 @@ void Actor::SetMagicEquipment(const MagicEquipment& acEquipment) noexcept
     auto* pEquipManager = EquipManager::Get();
     auto& modSystem = World::Get().GetModSystem();
 
-    if (acEquipment.LeftHandSpell)
+    // The owner may have magic from a mod this client doesn't have (e.g. a power a werewolf mod
+    // equips after transforming back). Such ids resolve to 0, and equipping a null form leaves the
+    // actor with an empty hand/voice entry that combat AI dereferences later (crash in
+    // Actor::VisitSpells while building the combat inventory). Skip anything that doesn't resolve.
+    const auto equipHandSpell = [&](const GameId& acSpellId, uint32_t aSlot, const char* apHand)
     {
-        uint32_t mainHandWeaponId = modSystem.GetGameId(acEquipment.LeftHandSpell);
-        spdlog::debug("Setting left hand spell: {:X}", mainHandWeaponId);
-        pEquipManager->EquipSpell(this, TESForm::GetById(mainHandWeaponId), 0);
-    }
+        const uint32_t cSpellId = modSystem.GetGameId(acSpellId);
+        auto* pSpell = Cast<MagicItem>(TESForm::GetById(cSpellId));
+        if (!pSpell)
+        {
+            spdlog::warn(
+                "Actor {:X}: skipping {} hand spell {:X}:{:X}, not a spell on this client (missing mod?)", formID, apHand, acSpellId.ModId, acSpellId.BaseId);
+            return;
+        }
+
+        spdlog::debug("Setting {} hand spell: {:X}", apHand, cSpellId);
+        pEquipManager->EquipSpell(this, pSpell, aSlot);
+    };
+
+    if (acEquipment.LeftHandSpell)
+        equipHandSpell(acEquipment.LeftHandSpell, 0, "left");
 
     if (acEquipment.RightHandSpell)
-    {
-        uint32_t secondaryHandWeaponId = modSystem.GetGameId(acEquipment.RightHandSpell);
-        spdlog::debug("Setting right hand spell: {:X}", secondaryHandWeaponId);
-        pEquipManager->EquipSpell(this, TESForm::GetById(secondaryHandWeaponId), 1);
-    }
+        equipHandSpell(acEquipment.RightHandSpell, 1, "right");
 
     if (acEquipment.Shout)
     {
-        uint32_t shoutId = modSystem.GetGameId(acEquipment.Shout);
-        spdlog::debug("Setting shout: {:X}", shoutId);
-        pEquipManager->EquipShout(this, TESForm::GetById(shoutId));
+        const uint32_t cShoutId = modSystem.GetGameId(acEquipment.Shout);
+        TESForm* pShout = TESForm::GetById(cShoutId);
+
+        // The voice slot holds either a shout or a power (a spell)
+        if (!Cast<TESShout>(pShout) && !Cast<MagicItem>(pShout))
+        {
+            spdlog::warn(
+                "Actor {:X}: skipping shout/power {:X}:{:X}, not a shout or power on this client (missing mod?)", formID, acEquipment.Shout.ModId,
+                acEquipment.Shout.BaseId);
+        }
+        else
+        {
+            spdlog::debug("Setting shout: {:X}", cShoutId);
+            pEquipManager->EquipShout(this, pShout);
+        }
     }
 }
 

Code/client/Games/Skyrim/Components/TESSpellList.cpp

@@ -10,3 +10,32 @@ void TESSpellList::Initialize()
 
     lists = Memory::New<Lists>();
 }
+
+namespace
+{
+template <class T> uint32_t CompactNonNull(T** apEntries, uint32_t& aCount) noexcept
+{
+    if (!apEntries)
+        return 0;
+
+    uint32_t kept = 0;
+    for (uint32_t i = 0; i < aCount; ++i)
+    {
+        if (apEntries[i])
+            apEntries[kept++] = apEntries[i];
+    }
+
+    const uint32_t cRemoved = aCount - kept;
+    aCount = kept;
+    return cRemoved;
+}
+} // namespace
+
+uint32_t TESSpellList::RemoveNullEntries() noexcept
+{
+    if (!lists)
+        return 0;
+
+    return CompactNonNull(lists->spells, lists->spellCount) + CompactNonNull(lists->unk4, lists->unk4Count) +
+           CompactNonNull(lists->shouts, lists->shoultCount);
+}

Code/client/Games/Skyrim/Components/TESSpellList.h

@@ -21,6 +21,8 @@ struct TESSpellList : BaseFormComponent
     Lists* lists;
 
     void Initialize();
+    // Drops null spells/shouts left by a change-form load, returns how many were dropped
+    uint32_t RemoveNullEntries() noexcept;
 };
 
 static_assert(sizeof(TESSpellList::Lists) == 0x28);

Code/client/Games/Skyrim/Forms/EnchantmentItem.cpp

@@ -14,26 +14,42 @@ EnchantmentItem* EnchantmentItem::Create(const Inventory::EnchantmentData& aData
 
     ModSystem& modSystem = World::Get().GetModSystem();
 
-    GameArray<EffectItem> effects{};
-    effects.Resize(aData.Effects.size());
-    for (int i = 0; i < aData.Effects.size(); i++)
+    // Effects from a mod this client doesn't have resolve to null. Keep only the ones that exist here; a created
+    // enchantment with a null effect crashes the game as soon as it is displayed, equipped or applied.
+    Vector<EffectItem> resolvedEffects;
+    resolvedEffects.reserve(aData.Effects.size());
+    for (const Inventory::EffectItem& effect : aData.Effects)
     {
-        Inventory::EffectItem effect = aData.Effects[i];
+        auto* pEffectSetting = Cast<EffectSetting>(TESForm::GetById(modSystem.GetGameId(effect.EffectId)));
+        if (!pEffectSetting)
+        {
+            spdlog::warn("Dropping enchantment effect {:X}:{:X}, not found on this client (missing mod?)", effect.EffectId.ModId, effect.EffectId.BaseId);
+            continue;
+        }
 
         EffectItem effectItem{};
         effectItem.data.fMagnitude = effect.Magnitude;
         effectItem.data.iArea = effect.Area;
         effectItem.data.iDuration = effect.Duration;
         effectItem.fRawCost = effect.RawCost;
-        effectItem.pEffectSetting = Cast<EffectSetting>(TESForm::GetById(modSystem.GetGameId(effect.EffectId)));
-        if (!effectItem.pEffectSetting)
-            spdlog::error("Effect setting not found: {:X}:{:X}", effect.EffectId.ModId, effect.EffectId.BaseId);
+        effectItem.pEffectSetting = pEffectSetting;
 
         // TODO: TESCondition?
 
-        effects[i] = effectItem;
+        resolvedEffects.push_back(effectItem);
+    }
+
+    if (resolvedEffects.empty())
+    {
+        spdlog::warn("Not creating enchantment, none of its {} effects exist on this client", aData.Effects.size());
+        return nullptr;
     }
 
+    GameArray<EffectItem> effects{};
+    effects.Resize(resolvedEffects.size());
+    for (size_t i = 0; i < resolvedEffects.size(); i++)
+        effects[i] = resolvedEffects[i];
+
     BGSCreatedObjectManager* objManager = BGSCreatedObjectManager::Get();
 
     EnchantmentItem* pItem = nullptr;

Code/client/Games/Skyrim/Projectiles/Projectile.cpp

@@ -97,12 +97,20 @@ BSPointerHandle<Projectile>* TP_MAKE_THISCALL(HookLaunch, BSPointerHandle<Projec
 
     auto result = TiltedPhoques::ThisCall(RealLaunch, apThis, arData);
 
-    TP_ASSERT(result, "No projectile handle returned.");
+    if (!result)
+    {
+        spdlog::warn("No projectile handle returned, not syncing the launch");
+        return result;
+    }
 
+    // There is nothing to sync when the returned handle doesn't resolve to a projectile.
     TESObjectREFR* pObject = TESObjectREFR::GetByHandle(result->handle.iBits);
     Projectile* pProjectile = Cast<Projectile>(pObject);
-
-    TP_ASSERT(pProjectile, "No projectile found.");
+    if (!pProjectile)
+    {
+        spdlog::warn("No projectile found for handle {:X}, not syncing the launch", result->handle.iBits);
+        return result;
+    }
 
     Event.Power = pProjectile->fPower;
 

Code/client/Games/Skyrim/TESObjectREFR.cpp

@@ -622,9 +622,14 @@ ExtraDataList* TESObjectREFR::GetExtraDataFromItem(const Inventory::Entry& arEnt
             pEnchantment = Cast<EnchantmentItem>(TESForm::GetById(enchantId));
         }
 
-        TP_ASSERT(pEnchantment, "No Enchantment created or found.");
-
-        pExtraDataList->SetEnchantmentData(pEnchantment, arEntry.ExtraEnchantCharge, arEntry.ExtraEnchantRemoveUnequip);
+        // Null when the enchantment (or all of a created one's effects) comes from a mod this client doesn't have.
+        // Attaching a null enchantment crashes later when the item is equipped or shown, so sync the item without it.
+        if (pEnchantment)
+            pExtraDataList->SetEnchantmentData(pEnchantment, arEntry.ExtraEnchantCharge, arEntry.ExtraEnchantRemoveUnequip);
+        else
+            spdlog::warn(
+                "Item {:X}:{:X}: skipping enchantment {:X}:{:X}, not available on this client (missing mod?)", arEntry.BaseId.ModId, arEntry.BaseId.BaseId,
+                arEntry.ExtraEnchantId.ModId, arEntry.ExtraEnchantId.BaseId);
     }
 
     if (arEntry.ExtraPoisonId != 0)