As there already exists a nullish coalescing operator (??), this implies a use case for an inverse nullish coalescing operator, which would still be a binary operator returning the second operand if the first one is not nullish (in contrast with ??).
Sample use-case: when fetching a possibly nullish relation:
let retrievedModel: Model | null = idOrNull === null ? null : await database.fetch<Model>(idOrNull); // the way it can be achieved now let retrievedModel: Model | null = idOrNull !? await database.fetch<Model>(idOrNull); // inverse null coalescing operator !?
An analogic use case would involve a value of undefined or a union of undefined and null, analogically to the null coealescing operator.