Reload data if slice binding returns null at rendering time.

We are not able to guarantee the binding results in the pre-check and
real binding would always be the same sinc slice may decide what it
would be based on some conditions. Hence, we should reload data and
refresh UI when it comes to null to prevent from blank suggestion.

Bug: 120221527
Test: visual
Change-Id: I79790edfe7fc3af7b9c3b3a7df6a7ffa7d405d50