Unable to catch HTTP exceptions.

[Details] (Vague example) Right now, Oak is not throwing any error for non-existent routes. Even though the response code is set to 404, it is not interpreted as an error, thus it never gets to the error handling middleware.

[Error handling middleware] (Vague + pseudocode)

try {
await next()
} catch(error) {
response.body = `This is an error ${error.toString()}`
}

In theory, if an error was thrown because of the 404 route, it would return a response as shown above, but as an error is never thrown this never happens.

On the other hand, when I do this middleware:

await next();
console.log(context.response.status);

I can clearly see how it logs a 404 in the console.

[kaleidawave]

It could maybe implemented as a opt in. I don’t think it would be too hard to implement support for new Application({throwOnNotFound: true}) or something like that

[kitsonk]

Having thought about this (yeah, I know, long time) and how the koa-router handles this, I think the current behaviour is what is expected, and that users should have a middleware that handles non-matched routes, as that is ultimately what stacked middleware should do, so having a 404 middleware that sets the right behaviours for the application at the end should be a common pattern. There are several examples of this in both koa and express.