Protect against the case where the current inlined depth is wrong, and leads us to think we can't even get the
frame at index 0.  We should ALWAYS be able to get that.

<rdar://problem/13497571>


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@178205 91177308-0d34-0410-b5e6-96231b3b80d8