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We spent all this time on air handling.

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So now surely there is no way that we could break everything by just adding in one keyword.

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Right.

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There's no way that could possibly happen.

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Oh whoops.

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Yeah.

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Turns out we can break all the error handling stuff we just did by adding in one very small keyword.

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So in this video we can take a look at what that keyword is.

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We're gonna understand what it does to us and how we're gonna solve it and make it work with our area

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handling approach.

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Gonna find that little apt on all statement we just added in a moment ago and I'm gonna put it on the

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async keyword like so now surely that's not going to do anything to us right.

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We don't actually have any await syntax inside of your.

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All we're doing is throwing in an error.

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Well let's save this.

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Go back over to post man and make that same request once again Hey wait a minute it's stuck in sending

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request.

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What's going on here.

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How did we just break this by adding on that one little keyword Well you've got to understand what async

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does behind the scenes.

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Never you mark a function as async that function is no longer going to immediately return any value.

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Instead it's going to return a promise that's going to resolve with some value in the future even if

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we throw in error inside there.

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How does this relate to express.

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Well let's go back to the Express error handling documentation once again.

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You might recall that I had mentioned very briefly that if we had a synchronous root handler and we

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threw an Air Express will automatically capture that thing and throw it off to any error handling middleware

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we have to find inside of our application.

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However if we have an asynchronous middleware or an asynchronous root handler and when we say asynchronous

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we are talking about any root handler that's going to have a secured applied to it a callback or a promise.

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Then we have to rely upon this next function instead and that's what we just did.

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We now have an asynchronous root handler.

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So if you want this thing to work correctly we have to receive that next function.

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And when we decide to throw in error we don't actually throw it.

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Instead we will call next with our air let's now save this look back over to man and try this again.

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Looks like it's working once again.

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Well obviously rather than doing the throw new air versus next I would rather not have to worry about

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this next thing at all.

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It's something it's very particular to express and it really requires engineers to understand what next

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is doing behind the scenes I think would be a lot better if we could somehow figure out a way to stick

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with the throw keyword instead and just make this work.

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Well to do so we're going to install a little package a little package that's going to change the default

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behavior of how express handles root handlers like the one we just put together right here.

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This little package is going to make sure that express waits or essentially does in a weight statement

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on this function.

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And so if we have some async code inside of here for example using async await express we'll start to

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watch for any errors that we throw at any point time inside this function but essentially it's just

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augmenting the default behavior of Express and kind of bringing it into the present age of using async

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await.

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This package is extremely easy to use.

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Let's just go take a look at the documentation for it.

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Very quickly I'm going to open up NPM the NPM J.S. dot com and at the top I'm going to do a search.

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We're going to look for I do not recall the name of it off the top I had a gotta check my notes really

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quickly.

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There we go.

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Turns out there's a dozen packages with very similar name which is why I didn't really just want to

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randomly search for it so express async errors.

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That's what we're looking for.

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So here's express async errors you can read the documentation here if you want to.

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It pretty much just does what I mentioned.

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It's going to make sure that if we ever throw an error at some point time inside of an async function

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this whole package is going to make sure that express listens for it.

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Use this thing.

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All we have to do is install it and then require it in or in our case import it in right after Express

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that's it.

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That's all we have to do so let's go over to our terminal and install it into our project

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inside of our ticketing directory.

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I'll change into off and do an npm install express async errors.

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This is a very small module so it should install rather quickly after installing it all then go backwards

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my index start to yes file a go up to the top I'll find where we import express and then right after

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that I'll add an import express async errors and that should be at I'll save this.

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You'll notice that I still have code that was causing us trouble a moment ago.

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But if I go backward a postman and send a request once again.

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Now it's working and even though we've got that async keyword in there.

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So this is going to fix up not only the root handlers we define inside this file but inside of other

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files as well.

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So for example if we go back over to sign up here's the sign up file find the actual root handling function

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and put the async keyword on there as well.

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Now we can go backward a postman I'll fix up my URL so going to delete all that gibberish at the end.

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I'll make sure I'm still making a post request.

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Now if I send this off.

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Yeah this works as well.

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Well I'd say this looks pretty good.

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Now we can handle errors across the board and I'm pretty sure that really actually is the last error

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related topic we need to worry about for a long time.

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So with that in mind because right here in a start taking a look at actual authentication is what we

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actually originally set out to do in just a moment.