Fix #1799: Add a special warning if BEE is installed directly into th…

…e game folder.

src/BEE2_launch.pyw

@@ -50,7 +50,14 @@ if __name__ == '__main__':
     import localisation
     localisation.setup(LOGGER)
 
-    if app_name == 'bee2':
+    # Check early on for a common mistake - putting the BEE2 folder directly in Portal 2 means
+    # when we export we'll try and overwrite ourself. Use Steam's appid file as a marker.
+    if utils.install_path('../steam_appid.txt').exists() and utils.install_path('.').name.casefold() == 'bee2':
+        from app import gameMan
+        gameMan.app_in_game_error()
+        sys.exit()
+
+    elif app_name == 'bee2':
         from app import BEE2
         BEE2.start_main()
     elif app_name == 'backup':

src/app/gameMan.py

@@ -1263,6 +1263,20 @@ def logic_pos() -> Iterator[Vec]:
     )
 
 
+def app_in_game_error() -> None:
+    """Display a message warning about the issues with placing the BEE folder directly in P2."""
+    messagebox.showerror(
+        message=gettext(
+            "It appears that the BEE2 application was installed directly in a game directory. "
+            "The bee2/ folder name is used for exported resources, so this will cause issues.\n\n"
+            "Move the application folder elsewhere, then re-run."
+        ),
+        parent=TK_ROOT,
+        title='BEE2',
+    )
+    return None
+
+
 def save() -> None:
     for gm in all_games:
         gm.save()