alterErrors

window.nvtag_callbacks = window.nvtag_callbacks || {};
window.nvtag_callbacks.alterErrors = window.nvtag_callbacks.alterErrors || [];

window.nvtag_callbacks.alterErrors.push(function (args) {
    if (args.field_name === 'FirstName') {
        if (args.errors && args.errors.length > 0) {
            args.errors = ["YOU MUST GIVE US YOUR FIRST NAME TO PROCEED"];
        } else {
            if (args.val !== "Frank") {
                args.errors = ["We only accept a first name of Frank"];
            }
        }
    }
    return args;
});