Polish remove_links migration script

Author: blkerby

scripts/migrations/remove_links.py

@@ -1,15 +1,22 @@
 # This script removes occurrences of `links` in room files.
-
+# 
+# To use, run "PYTHONPATH=. python migrations/remove_links.py"
+# from a working directory of "sm-json-data/scripts".
 import json
 from pathlib import Path
-import copy
-
+import argparse
 import format_json
 
+argparser = argparse.ArgumentParser()
+argparser.add_argument("--path", type=Path, default="../region", help="Path to the region directory")
+args = argparser.parse_args()
 
-for path in sorted(Path("../../region").glob("**/*.json")):
+if not args.path.exists():
+    raise FileNotFoundError(f"Path {args.path} does not exist")
+for path in sorted(args.path.glob("**/*.json")):
     room_json = json.load(path.open("r"))
-    if room_json.get("$schema") != "../../../schema/m3-room.schema.json":
+    schema = room_json.get("$schema")
+    if schema is None or schema.split("/")[-1] != "m3-room.schema.json":
         continue
     print("Processing", path)
     del room_json["links"]