Added missing root folder check in trainer battle type migration script (#6944)

migration_scripts/1.12/convert_trainer_battle_types.py

@@ -1,4 +1,5 @@
 import re
+import os
 
 def trainer_battle_types(data):
     data = re.sub(re.escape("Double Battle: No"), "Battle Type: Singles", data)
@@ -6,6 +7,10 @@ def trainer_battle_types(data):
 
     return data
 
+if not os.path.exists("Makefile"):
+    print("Please run this script from your root folder.")
+    quit()
+
 with open('src/data/trainers.party', 'r') as file:
     data = file.read()
 with open('src/data/trainers.party', 'w') as file: