fixed panic if loadfunc returns nil with no error

hwsauth/authenticate.go

@@ -2,6 +2,7 @@ package hwsauth
 
 import (
 	"net/http"
+	"reflect"
 	"time"
 
 	"git.haelnorr.com/h/golib/jwt"
@@ -45,6 +46,9 @@ func (auth *Authenticator[T, TX]) getAuthenticatedUser(
 	if err != nil {
 		return authenticatedModel[T]{}, errors.Wrap(err, "auth.load")
 	}
+	if reflect.ValueOf(model).IsNil() {
+		return authenticatedModel[T]{}, errors.New("no user matching JWT in database")
+	}
 	authUser := authenticatedModel[T]{
 		model: model,
 		fresh: aT.Fresh,