prebidcache module ignores invalid response

[dmitriyshashkin]

Type of issue

Bug

Description

https://github.com/prebid/Prebid.js/blob/master/src/videoCache.js#L125
If Cache server responds with some non-JSON response (like Xandr's cache solution does) the response is silently ignored

Steps to reproduce

1. Setup HB video stack. Use this for the cache server "url":"https://ib.adnxs.com/prebid/cache"
2. Enable debug output
3. Add some test bidder that always bid
4. Request bids

Test page

https://js-debug-2.b-cdn.net/prebid_video_cache/mediaMetadata.html

Expected results

Some error message in console

Actual results

Bid is discarded, no error message is issued

Platform details

Any

Other information

Why I consider it a bug:

1. If server responds with 502 or if it responds with JSON without UUIDs I get error message. It is illogical to hide error in one particular case, that is when response is not a valid JSON
2. It makes debugging much harder. Problem with cache server can lead to valid bids being discarded. But the problem does not manifest itself in the debug log.
3. Invalid JSON response is not an expected response. It indicates that there is a problem with the server. Therefore it should not get ignored.