Dear Mongoers,
I need help with some weird TS error I get only when using findOneAndUpdate in Node JS. This sometimes works, sometimes not! 
The situation is about event management. If a user joins the event, they can either book a spot, or join the waiting list:
I am using Node JS with TS. TS sometimes complains about this:
const list = numberJoined < capacity ? "joined" : "waitingList";
const counterList = list === "joined" ? "waitingList" : "joined";
const event = await db?.collection("events-jordan").findOneAndUpdate(
{ _id: new ObjectId(eventId) },
{
$addToSet: {
[list]: userId,
},
$pull: {
[counterList]: userId,
},
},
{ returnDocument: "after" }
)
I get the following error from TS which I am unable to solve
No overload matches this call.
Overload 2 of 4, ‘(filter: Filter, update: UpdateFilter, options: FindOneAndUpdateOptions): Promise<…> | undefined’, gave the following error.
Type ‘{ [x: string]: string; }’ is not assignable to type ‘SetFields’.
Type ‘{ [x: string]: string; }’ is not assignable to type ‘NotAcceptedFields<Document, readonly any | undefined>’.
‘string’ index signatures are incompatible.
Type ‘string’ is not assignable to type ‘undefined’.
Overload 2 of 4, ‘(filter: Filter, update: UpdateFilter, options: FindOneAndUpdateOptions): Promise<…> | undefined’, gave the following error.
Type ‘{ [x: string]: string; }’ is not assignable to type ‘PullOperator’.
Type ‘{ [x: string]: string; }’ is not assignable to type ‘{ readonly [x: string]: Partial | { [x: string]: FilterOperators | undefined; } | FilterOperators | undefined; }’.
‘string’ index signatures are incompatible.
Type ‘string’ is not assignable to type ‘Partial | { [x: string]: FilterOperators | undefined; } | FilterOperators | undefined’.ts(2769)
mongodb.d.ts(5770, 5): The expected type comes from property ‘$addToSet’ which is declared here on type ‘UpdateFilter’
mongodb.d.ts(5772, 5): The expected type comes from property ‘$pull’ which is declared here on type ‘UpdateFilter’
Any help is very much appreciated.
Thank you 