Catch Error from gapi.client.load

Question

I'm using Google App Engine with Java and Google Cloud Endpoints. In my JavaScript front end, I'm using this code to handle initialization, as recommended:

var apisToLoad = 2;
var url = '//' + $window.location.host + '/_ah/api';
gapi.client.load('sd', 'v1', handleLoad, url);
gapi.client.load('oauth2', 'v2', handleLoad);
function handleLoad() {
    // this only executes once,
    if (--apisToLoad === 0) {
        // so this is not executed
    }
}

How can I detect and handle when gapi.client.load fails? Currently I am getting an error printed to the JavaScript console that says: Could not fetch URL: https://webapis-discovery.appspot.com/_ah/api/static/proxy.html). Maybe that's my fault, or maybe it's a temporary problem on Google's end - right now that is not my concern. I'm trying to take advantage of this opportunity to handle such errors well on the client side.

So - how can I handle it? handleLoad is not executed for the call that errs, gapi.client.load does not seem to have a separate error callback (see the documentation), it does not actually throw the error (only prints it to the console), and it does not return anything. What am I missing? My only idea so far is to set a timeout and assume there was an error if initialization doesn't complete after X seconds, but that is obviously less than ideal.

Edit:

This problem came up again, this time with the message ERR_CONNECTION_TIMED_OUT when trying to load the oauth stuff (which is definitely out of my control). Again, I am not trying to fix the error, it just confirms that it is worth detecting and handling gracefully.

Answer 1

I know this is old but I came across this randomly. You can easily test for a fail (at least now).

Here is the code:

gapi.client.init({}).then(() => {
     gapi.client.load('some-api', "v1", (err) => { callback(err) }, "https://someapi.appspot.com/_ah/api");
}, err, err);

function callback(loadErr) {
    if (loadErr) { err(loadErr); return; }
    // success code here 
}

function err(err){
     console.log('Error: ', err);
     // fail code here
}

Example