From c7a2ef337197ae1acfd6cd3cf8577b6b4a904a4f Mon Sep 17 00:00:00 2001
From: iriv24 <40581123+iriv24@users.noreply.github.com>
Date: Sun, 15 Dec 2024 10:04:06 -0500
Subject: [PATCH] Prevent Key Items that open other menus from causing a crash
 if registered and used from the field (#5810)

---
 src/item_use.c | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/src/item_use.c b/src/item_use.c
index c04d9b9911..c9be4f5caa 100644
--- a/src/item_use.c
+++ b/src/item_use.c
@@ -1400,9 +1400,17 @@ void ItemUseOutOfBattle_ZygardeCube(u8 taskId)
 
 void ItemUseOutOfBattle_Fusion(u8 taskId)
 {
-    gItemUseCB = ItemUseCB_Fusion;
-    gTasks[taskId].data[0] = FALSE;
-    SetUpItemUseCallback(taskId);
+    if (!gTasks[taskId].tUsingRegisteredKeyItem)
+    {
+        gItemUseCB = ItemUseCB_Fusion;
+        gTasks[taskId].data[0] = FALSE;
+        SetUpItemUseCallback(taskId);
+    }
+    else
+    {
+        // TODO: handle key items with callbacks to menus allow to be used by registering them.
+        DisplayDadsAdviceCannotUseItemMessage(taskId, gTasks[taskId].tUsingRegisteredKeyItem);
+    }
 }
 
 void Task_UseHoneyOnField(u8 taskId)
@@ -1552,10 +1560,18 @@ static void ItemUseOnFieldCB_TownMap(u8 taskId)
 
 void ItemUseOutOfBattle_TownMap(u8 taskId)
 {
-    sItemUseOnFieldCB = ItemUseOnFieldCB_TownMap;
-    gFieldCallback = FieldCB_UseItemOnField;
-    gBagMenu->newScreenCallback = CB2_ReturnToField;
-    Task_FadeAndCloseBagMenu(taskId);
+    if (!gTasks[taskId].tUsingRegisteredKeyItem)
+    {
+        sItemUseOnFieldCB = ItemUseOnFieldCB_TownMap;
+        gFieldCallback = FieldCB_UseItemOnField;
+        gBagMenu->newScreenCallback = CB2_ReturnToField;
+        Task_FadeAndCloseBagMenu(taskId);
+    }
+    else
+    {
+        // TODO: handle key items with callbacks to menus allow to be used by registering them.
+        DisplayDadsAdviceCannotUseItemMessage(taskId, gTasks[taskId].tUsingRegisteredKeyItem);
+    }
 }
 
 #undef tUsingRegisteredKeyItem