Cloud Functions: Promises must be handled appropriately

Question

Since I upgraded Cloud Functions for Firebase to Node8 and ES17 a TsLint error shows up when trying to update a function. It throws Promises must be handled appropriately for this chunk of code:

app.get('*', (req, res) => {
    const isBot = detectBot(req.headers['user-agent']);

    if (isBot) {
        const botUrl = generateUrl(req);
        // If bot, fetch url via rendertron
        fetch(`https://foo.com/render/${botUrl}`)
            .then(rendertronRes => rendertronRes.text())
            .then(body => {
                res.set('Cache-Control', 'public, max-age=300, s-maxage=600');
                res.set('Vary', 'User-Agent');

                res.send(body.toString());
            });
    } else {
        // Not a bot, fetch the regular Angular app
        fetch('https://bar.com/')
            .then(regularRes => regularRes.text())
            .then(body => {
                res.send(body.toString());
            })
            .catch(err => res.send(err));
    }
});

The strangest part is that it complains about the second fetch, but not the first.

Answer 1

Try to write catch block for each then