Message "%s" does not resolve to "" when argument is not passed into Error

### Prerequisites - [X] I have written a descriptive issue title - [X] I have searched existing issues to ensure the bug has not already been reported ### Fastify version 4.26.0 ### Plugin version _No response_ ### Node.js version 22.3.0 ### Operating system Linux ### Operating system version (i.e. 20.04, 11.3, 10) 20.04.6 ### Description I'm not sure if this is a bug or a feature request. Please correct me one way or the other. I'm trying to support the following functionality: ```ts export const Unauthorized = createError("MY_UNAUTHORIZED", "%s", 403); throw new Unauthorized("You cannot do this") // { "code": "MY_UNAUTHORIZED", "Bad Request", "message": "You cannot do this", "statusCode": 403 } throw new Unauthorized() // { "code": "MY_UNAUTHORIZED", "Bad Request", "message": "", "statusCode": 403 } ``` However, the second case resolves to: ```ts throw new Unauthorized() // { "code": "MY_UNAUTHORIZED", "Bad Request", "message": "%s", "statusCode": 403 } // Note the "%s" in the message. ``` This is consistent with how `node:util`'s `format` works, but I don't think it's useful here. I think a blank message, rather than "%s", is preferable in this scenario. ### Link to code that reproduces the bug _No response_ ### Expected Behavior _No response_