Added custom error for could not get User ID from JWT

models/error.go

@@ -104,4 +104,16 @@ func (err ErrBookTitleCannotBeEmpty) Error() string {
 	return fmt.Sprintf("the book should at least have a title")
 }
 
+// ErrCouldNotGetUserID represents a "ErrCouldNotGetUserID" kind of error.
+type ErrCouldNotGetUserID struct {}
+
+// ErrBookTitleCannotBeEmpty checks if an error is a ErrBookTitleCannotBeEmpty.
+func IsErrCouldNotGetUserID(err error) bool {
+	_, ok := err.(ErrCouldNotGetUserID)
+	return ok
+}
+
+func (err ErrCouldNotGetUserID) Error() string {
+	return fmt.Sprintf("could not get user ID")
+}
 

models/user.go

@@ -87,7 +87,7 @@ func GetCurrentUser(c echo.Context) (user User, err error) {
 	claims := jwtinf.Claims.(jwt.MapClaims)
 	userID, ok := claims["id"].(float64)
 	if !ok {
-		return user, fmt.Errorf("Error getting UserID")
+		return user, ErrCouldNotGetUserID{}
 	}
 	user = User{
 		ID:       int64(userID),