Complaint

Mobile pubs sometimes report a crash on interstitial requests like:

500 error type: Critical error while running the auction: null

(talk to me in Prebid Slack I'll give you a curl)

Root cause analysis

formats is not null-checked here in the Index Exchange adapter:

and it causes a crash when there was no formats specified and no matching sizes were computed due to device.ext.prebid.interstitial.min[width/height]perc being too high or not specified. imp will be returned unaltered from here in either of those cases:

Fix options

1. implement a null check and a test case (but other adapters may have similar failures, thus see option 2)
2. ensure formats is always an array before sending it to bid adapters either empty or with at least one size (but which?)