Error when `NewClaimsFunc` returns value object

[178inaba]

Edit the sample below so that NewClaimsFunc returns a value object.
https://echo.labstack.com/docs/cookbook/jwt

NewClaimsFunc: func(c echo.Context) jwt.Claims {
	return jwtCustomClaims{}
},

The following error occurs.

token is malformed: could not JSON decode claim: json: cannot unmarshal object into Go value of type jwt.Claims

I think it would be a good idea to add a check to see if Claims is a pointer.
Below is an example of a json package.
https://cs.opensource.google/go/go/+/refs/tags/go1.22.2:src/encoding/json/decode.go;l=172-175

I also think it would be effective to add this to the NewClaimsFunc documentation.