The other half of the checkin to produce better error messages when the ThreadPlanCallFunction isn't valid.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@178203 91177308-0d34-0410-b5e6-96231b3b80d8
Use the error from ValidatePlan.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@178204 91177308-0d34-0410-b5e6-96231b3b80d8