message: When looking for the start of an line, ignore if there's no debug info
  * When searching for the start of a range of instructions mapped to a single
  line when stepping backwards, we need to ignore instructions that don't have
  any debug info because they will look like a 'different' smaller stack.
diff: @@ -2170,8 +2170,8 @@ bool ShaderViewer::step(bool forward, StepMode mode)
  // keep going until we hit the closest instruction of any block that maps to this function
  while(!IsFirstState() && !targetInsts.contains(GetCurrentState().nextInstruction))
  {
  - if((oldStack == GetPreviousState().callstack ||
  - oldStack.size() > GetPreviousState().callstack.size()) &&
  + const rdcarray<rdcstr> &prevStack = GetPreviousState().callstack;
  + if((oldStack == prevStack || (!prevStack.empty() && oldStack.size() > prevStack.size())) &&
  !oldLine.SourceEqual(GetPreviousInstInfo().lineInfo))
  {
  // if we hit this case, it means we jumped to an instruction in the same call which maps
  