Description of problem:

Error is displaying on moving the sink from one knative service to another knative service

Prerequisites (if any, like setup, operators/versions):

knative operator needs to be installed with knative eventing and serving subscription

Steps to Reproduce

1. Create Knative services "nodejs-ex-git-1" and "nodejs-ex-git"

2. And user has created sinkbinding "sink-binding"
   When user clicks on event source "sink-binding" to open side bar
   And user selects "Move sink" from side bar Action menu
   And user selects the knative service "nodejs-ex-git-1" from Resource dropdown
   And user clicks save on Move Sink modal
   Then 
    

Actual results:

Error is displaying as shown in the image

Expected results:

user will see that event source "sink-binding" is sinked with knative Service "nodejs-ex-git-1"

Reproducibility (Always/Intermittent/Only Once):

Always

Build Details:

4.8.0-0.nightly-2021-03-18-075013

Additional info:

If we cancel and repeat the move sink operation, then it works