ios - XCode6 runtime error after modifying asset catalogue -

i playing around asset categories in xcode 6.4 when starting running runtime error upon loading app:

"terminating app due uncaught exception 'nsinvalidargumentexception', reason: 'cannot comparison query type: (null)'... ...libc++abi.dylib: terminating uncaught exception of type nsexception"

i tried setting "app icon source" & "launch screen image source" "don't use asset catalogue" , doing new migration, tried deleting images.xcassets file , re-creating. deleting images , re-importing, can't seem fix error.

i didn't modify code between time app working , when error started happening... ideas? i'm stuck on one...