MustLocalize panics even when DefaultMessage is specified

[Dawid Wysokiński]

Version: 2.1.1
Code:

const InternalServerError = "internalServerError"

func FallbackMsg(id string, msg string) *i18n.Message {
	return &i18n.Message{
		ID:    id,
		One:   msg,
		Many:  msg,
		Other: msg,
	}
}

localizer.MustLocalize(&i18n.LocalizeConfig{
	MessageID: InternalServerError,
	DefaultMessage: FallbackMsg(InternalServerError,
		"{{.Mention}} Internal server error occurred, please try again later."),
		TemplateData: map[string]interface{}{
			"Mention": "Adam",
		},
})

Error: message "internalServerError" not found in language "language tag"

In the older version (v2.0.3) everything works fine, something is wrong with the update.

[Nick Snyder]

Yeah, there is a behavior change here. It is now considered an error if we fallback to a language that wasn't requested by the client. If you don't want this to be an error, then you can include the default locale in the call to NewLocalizer.