CODEWITHSUNDEEP
typescripthttprequestaurelia
Maha Waqar
Maha Waqar

Reputation: 643

What can be the possible cause of 'Unhandled Promise Rejection: TypeError' in aurelia?

I have been into Aurelia development but took break for two months. Now I have started a new project in it and I am encountering an unknown issue when trying to use http-fetch-client.

Console shows:

aurelia-fetch-client.js?a909:199 OPTIONS http://url.com/api/login net::ERR_CONNECTION_REFUSED

index.js?07f7:248 Possible Unhandled Promise Rejection: TypeError: Failed to fetch

Network tab shows:

Request URL: http://url.com/api/login
Referrer Policy: no-referrer-when-downgrade

To my surprise, my previous project (that was executing fetch client request successfully two months ago) is also showing this error now. Can anyone give insight over this issue? Why am I encountering this?

Upvotes: 1

Views: 428

Answers (1)

Alex Dresko
Alex Dresko

Reputation: 5203

It sounds like you're doing async/await, and you haven't wrapped your await call in a try/catch.

Some versions of Aurelia use Bluebird as a Promise shim, and you can use their global rejection events to deal with those problems.

Here's what that looks like. 

// NOTE: event name is all lower case as per DOM convention
window.addEventListener("unhandledrejection", function(e) {
    // NOTE: e.preventDefault() must be manually called to prevent the default
    // action which is currently to log the stack trace to console.warn
    e.preventDefault();
    // NOTE: parameters are properties of the event detail property
    var reason = e.detail.reason;
    var promise = e.detail.promise;
    // See Promise.onPossiblyUnhandledRejection for parameter documentation
});

// NOTE: event name is all lower case as per DOM convention
window.addEventListener("rejectionhandled", function(e) {
    // NOTE: e.preventDefault() must be manually called prevent the default
    // action which is currently unset (but might be set to something in the future)
    e.preventDefault();
    // NOTE: parameters are properties of the event detail property
    var promise = e.detail.promise;
    // See Promise.onUnhandledRejectionHandled for parameter documentation
});

Of course, you might be using a different Promise shim. But, ultimately, try/catch is your answer.

Upvotes: 1

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