fix: SocketIO JSON dumps with sane defaults

Similar to how `engineio` provides a JSON-compatible module, this change
adds a custom JSON encoder with support for additional types.

Changing SocketIO's JSON module fixes the encoding issue when the
scanning process tried to send a datetime, failing and the frontend not
displaying the scanned game (commonly, when it had sibling games)

backend/handler/socket_handler.py

@@ -1,5 +1,6 @@
 import socketio  # type: ignore
 from config import REDIS_URL
+from utils import json as json_module
 
 
 class SocketHandler:
@@ -7,6 +8,7 @@ class SocketHandler:
         self.socket_server = socketio.AsyncServer(
             cors_allowed_origins="*",
             async_mode="asgi",
+            json=json_module,
             logger=False,
             engineio_logger=False,
             client_manager=socketio.AsyncRedisManager(str(REDIS_URL)),

backend/utils/json.py

@@ -0,0 +1,29 @@
+"""JSON-compatible module with sane defaults.
+
+Inspiration taken from `python-engineio`.
+https://github.com/miguelgrinberg/python-engineio/blob/main/src/engineio/json.py
+"""
+
+import datetime
+import decimal
+import json
+import uuid
+from json import *  # noqa: F401, F403
+from json import dumps as __original_dumps
+from typing import Any
+
+
+class DefaultJSONEncoder(json.JSONEncoder):
+    """Custom JSON encoder that supports encoding additional types."""
+
+    def default(self, o: Any) -> Any:
+        if isinstance(o, (datetime.date, datetime.datetime, datetime.time)):
+            return o.isoformat()
+        if isinstance(o, (decimal.Decimal, uuid.UUID)):
+            return str(o)
+        return super().default(o)
+
+
+def dumps(*args: Any, **kwargs: Any) -> str:  # type: ignore[no-redef]
+    kwargs.setdefault("cls", DefaultJSONEncoder)
+    return __original_dumps(*args, **kwargs)