function chooseBestErrorMessage(error, alreadyTranslatedDefaultMessage, t) {
    const translateMessage = (message, number = null) => {
        if (number) {
            return t(message, {number});
        } else {
            return t(message);
        }
    };

    const setupSpecialMessages = () => {
        // eslint-disable-next-line no-shadow
        const t = message => specialMessages.push(message);
        if (specialMessages.length === 0) {
            // This formatting is intentionally weird. It causes the i18n-parser to pick these strings up.
            // Do not redefine this t. It's a local function and needs to stay that way.
            t('No member exists with this e-mail address. Please sign up first.');
            t('No member exists with this e-mail address.');
            t('This site is invite-only, contact the owner for access.');
            t('Unable to initiate checkout session');
            t('This site is not accepting payments at the moment.');
            t('Too many attempts try again in {number} minutes.');
            t('Too many attempts try again in {number} hours.');
            t('Too many attempts try again in {number} days.');
            t('Too many different sign-in attempts, try again in {number} minutes');
            t('Too many different sign-in attempts, try again in {number} hours');
            t('Too many different sign-in attempts, try again in {number} days');
            t('Failed to send magic link email');
            t('This site only accepts paid members.');
            t('Signups from this email domain are currently restricted.');
            t('Too many sign-up attempts, try again later');
            t('Memberships from this email domain are currently restricted.');
        }
    };

    const isSpecialMessage = (message) => {
        if (specialMessages.length === 0) {
            setupSpecialMessages();
        }
        if (specialMessages.includes(message)) {
            return true;
        }
        return false;
    };

    const prepareErrorMessage = (message = null) => {
        // Check for a number in message, if found, replace the number with {number} and return the number.
        // Assumes there's only one number in the message.
        if (!message) {
            return {preparedMessage: 'An error occurred', number: null};
        }
        const number = message.match(/\d+/);
        if (number) {
            message = message.replace(number[0], '{number}');
        }
        return {preparedMessage: message, number: number ? number[0] : null};
    };

    if (!error && !alreadyTranslatedDefaultMessage) {
        return t('An error occurred');
    }

    if (error instanceof HumanReadableError || error.message) {
        const {preparedMessage, number} = prepareErrorMessage(error.message);
        if (isSpecialMessage(preparedMessage)) {
            return translateMessage(preparedMessage, number);
        } else {
            return alreadyTranslatedDefaultMessage || translateMessage(error?.message);
        }
    } else {
        // use the default message if there's no error message
        // if we don't have a default message either, fall back to a generic message plus the actual error.
        return alreadyTranslatedDefaultMessage || t('An error occurred') + ': ' + error.toString();
    }
}
Attempt to return the best available message to the user, after translating it.
We detect special messages coming from the API for which we want to serve a specific translation.
Many "alreadyTranslatedDefaultMessages" are pretty vague, so we want to replace them with a more specific message
whenever one is available.