const ejs = require('ejs')
const path = require('path');
const fastify = require('fastify')();
const fastify_static = require('fastify-static');
const fastify_autoload = require('fastify-autoload');
const fastify_mongoose = require('fastify-mongoose');
const fastify_env = require('fastify-env');

let PORT;
let uri;

fastify.register(fastify_env, {
    dotenv: true,
    schema: {
        type: 'object',
        required: ['MONGO_URI', 'PORT'],
        properties: {
            MONGO_URI: {
                type: 'string',
                default: ''
            },
            PORT: {
                type: 'string',
                default: ''
            }
        }
    }
}).ready(err => {
    if (err) {
        throw new Error(err);
    }
    PORT = fastify.config.PORT;
    uri = fastify.config.MONGO_URI;
})

fastify.register(fastify_static, {
    root: path.join(__dirname, 'public'),
})

fastify.register(require('point-of-view'), {
    engine: {
        ejs: ejs,
    },
    root: path.join(__dirname, 'view')
})

fastify.register(fastify_autoload, {
    dir: path.join(__dirname, 'Logic/Routes'),
})

fastify.register(require('./Logic/Plugins/cache'))

fastify.register(fastify_mongoose, {
    uri: uri
})

const start = async () => {
    try {
        await fastify.ready();
        await fastify.listen(process.env.PORT);
        console.log('Listening on port: ', PORT);
    } catch (error) {
        throw new Error(error);
    }
}

start();

Error: Error: uri parameter is mandatory at D:\Users\Antonio\Desktop\Antonio\Work\GitHub\NextLevel\src\main.js:30:15

The problem is with fastify-mongoose, or probably with fastify-env. I explain: if i write directly the URI in the URI parameter, it works. But using environment variables no..