yael

// Create errors
err := yael.New("permission_denied").WithMeta("user", 123)

// Wrap one or more reasons
notAdminErr := yael.New("not_admin")
noRoleErr   := yael.New("no_role")
err = err.WithReasons(notAdminErr, noRoleErr)

// Satisfies Go's error interface
fmt.Println(err) // permission_denied

// Sentinel matching by code (errors.Is traverses all reasons)
errors.Is(err, notAdminErr) // true
errors.Is(err, noRoleErr)   // true

// JSON representable
{
    "code": "permission_denied",
    "meta": { "user": 123 },
    "reasons": [
        { "code": "not_admin" },
        { "code": "no_role" }
    ]
}