Ordering by a nullable relation

model UserPrisma {
  id            String @id @default(uuid())
  createdAt     DateTime @default(now())
  email         String @unique
  name          String
  surname       String

  reservations  ReservationPrisma[] @relation("reservation")
}

model ReservationPrisma {
  id            String @id @default(uuid()) 
  createdAt     DateTime @default(now())
  date          DateTime

  userId        String?
  user          UserPrisma? @relation("reservation", fields: [userId], references: [id], onDelete: Cascade)
}