Add new error code for segment fetch errors.

[OrenMe]

While investigating the request/response filters mechanism I saw you have different error propagation between license and other request/response types.
For license, no matter what error the underlying networking engine throws, the DRM engine will turn it to a LICENSE_REQUEST_FAILED error.
https://github.com/google/shaka-player/blob/e7a5bb9ecf07c5a0ac0d87d2a7a44e24d6a371f0/lib/media/drm_engine.js#L1122-L1140
For other types of requests the streaming engine will re-throw the networking engine error(last else clause, lines 1607-1614):
https://github.com/google/shaka-player/blob/e7a5bb9ecf07c5a0ac0d87d2a7a44e24d6a371f0/lib/media/streaming_engine.js#L1579-L1615
So if there was a filter request or response error the application using the player can know if it is a filter error or an actual HTTP error.
(the streaming engine actually does have also different handling for all of if-else clauses - so maybe this is also valid for them - you will not know that they failed due to filter error, like the license).

Is there a reason for this inconsistency in behaviour? does it serve a purpose?

[joeyparrish]

Is there a reason for this inconsistency in behaviour? does it serve a purpose?

Yes, but we're always open to feedback.

If we throw a generic networking error, you might not easily know it was a license request failure. You might want to handle a license request failure differently from some other networking failure. And if you want the original networking error, you can access it from error.data[0] as documented here: https://shaka-player-demo.appspot.com/docs/api/shaka.util.Error.html#value:6007

error.data[0] is a shaka.util.Error from the networking engine.

Does this make sense?

[OrenMe]

@joeyparrish this makes sense, but in this case shouldn’t the other way be aligned?
I mean, the streaming engine does emit the underlying network error as is in this case.
Should this be amended? And in this case is the request/response filter error should always be in the payload of their respective higher level engine/controller?
I’m wrapping shaka’s API with an abstraction later and also wondering if I should use the request/response filter error or report it as license/manifest/segment loading error.

[TheModMaker]

I guess that makes sense. We can add a new error code for SEGMENT_FETCH_ERROR to differentiate the source of the network error. This would be a breaking change since apps would no longer see errors like HTTP_ERROR anymore. We should also update the display in the demo app to handle these nested errors better.