We set the error when a breakpoint condition
doesn't return anything; that's great.

We should probably also return rather than
trying to access the nonexistent return value.

<rdar://problem/14009519>


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@184765 91177308-0d34-0410-b5e6-96231b3b80d8