Hmm I’m not sure what’s going on here. The error is from IntDecodeValue and the only integer field in your struct is GeoJSON.Accuracy so my guess is that the server is returning the accuracy field as a float instead of an integer.
One thing to try: instead of calling cur.Decode on the cursor from the Aggregate call, can you print out cur.Current (i.e fmt.Println(cur.Current))? This will print out the exact BSON document the driver received from the server and could help understand what field is malformed.
– Divjot