Change the way in which error case is being handled.

Change the way in which error case is being handled.

Specifically this:
* Prevents an "unused" warning in non-assert builds.
* In that error case return with out removing a child loop instead of
  looping forever.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231459 91177308-0d34-0410-b5e6-96231b3b80d8