Cache SW: Ensure any failure is always logged. #8328
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jridgewell
changed the title
src/service-worker/core.js
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| @@ -624,6 +624,10 @@ export function handleFetch(request, maybeClientId) { | |||
| // If not, let's fetch and cache the request. | |||
| return fetchJsFile(cache, versionedRequest, pathname, version); | |||
| }); | |||
| }).catch(err => { | |||
| // Throw error out of band. | |||
| Promise.reject(err); | |||
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"This throws the error out-of-band with the promise chain." If we didn't do this, the enclosing promise chain would be passed to event.respondWith, which installs a #catch block, which means it's rejection is handled. We have to create a new rejected promise that is not handled to get the unhandledrejection event.
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Doesn't this line just create a rejected promise? I thought you'd need to call the throw async to avoid having the promise swallow the error, e.g. with setTimeout.
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That's exactly what it does 😉. And because I don't attach a #catch block to it, its rejection won't ever be handled.
I could have also done a setTimeout and throw.
* Ensure any failure is always logged. * lint * Tell closure compiler it'll be alright.
If any failure happens in the promise chain, we want to hear about it. But unfortunately, the
event.respondWiththat we eventually pass the promise to will install a rejection handler, which means we won't get aunhandledrejectionevent.This throws the error out-of-band with the promise chain.