Issue with Generators in Rpc Middleware Implementations

Type 'Effect<symbol, never, never>' is not assignable to type 'Effect<unique symbol, never, never>' with 'exactOptionalPropertyTypes: true'. Consider adding 'undefined' to the types of the target's properties.
  Type 'symbol' is not assignable to type 'unique symbol'.ts(2375)
RpcMiddleware.ts(43, 18): The expected type comes from the return type of this signature.