joi is not defined

It seems like you're encountering an error message saying "joi is not defined". This error typically occurs when you are trying to use the `joi` library without importing or requiring it properly in your code.

To resolve this issue, you need to ensure that you have installed the `joi` library and imported it correctly in your code. If you are using Node.js, you can install it using npm or yarn by running the following command:

npm install joi

Then, in your code, make sure to import `joi` using one of the following methods:

// CommonJS style
const joi = require('joi');

// ES6 style
import joi from 'joi';

By doing so, you should be able to use the `joi` library without encountering the "joi is not defined" error.