Node JS Express Question.

import express, {Application, Request, Response, NextFunction} from "express";

const app: Application = express();

app.use(express.json());

app.get('/', (req: Request, res: Response): Object => {
    return res.json({status: "success", message: "Welcome to API Service"});
});

// MIDLEWARE #1
app.use((req: Request, res: Response, next: NextFunction) => {
    const error = new Error("Route not found.");
});

// MIDLEWARE #2
app.use((error: {message: string; status: number}, req: Request, res: Response, next: NextFunction) => {
    res.status(error.status || 500);
    res.json({
        status: 'error',
        message: error.message
    });
    next();
});

const PORT: any = process.env.PORT || 3000;

app.listen(PORT, () => console.log(`app listening on port ${PORT}`));

1) How middleware #1 know that the route not found? it suppose to run on every request?
2) Why does middleware #2 gets error as a parameter?