convert sets to list before sending event

Author: dlawin

data_diff/tracking.py

@@ -201,6 +201,12 @@ def create_email_signup_event_json(email: str) -> Dict[str, Any]:
     }
 
 
+def set_default(obj):
+    if isinstance(obj, set):
+        return list(obj)
+    raise TypeError
+
+
 def send_event_json(event_json):
     if not g_tracking_enabled:
         raise RuntimeError("Won't send; tracking is disabled!")
@@ -209,7 +215,7 @@ def send_event_json(event_json):
         "Content-Type": "application/json",
         "Authorization": "Basic MkhndE00SGNxOUJtZWlDcU5ZaHo3Tzl0a2pNOg==",
     }
-    data = json.dumps(event_json).encode()
+    data = json.dumps(event_json, default=set_default).encode()
     try:
         req = urllib.request.Request(TRACK_URL, data=data, headers=headers)
         with urllib.request.urlopen(req, timeout=TIMEOUT) as f: