message: Fix debugging function calls without return values
diff: @@ -929,12 +929,12 @@ void ThreadState::StepNext(ShaderDebugState *state,
  }
  else
  {
  + returnValue.name = "<return value>";
  if(opdata.op == Op::ReturnValue)
  {
  OpReturnValue ret(it);
  returnValue = GetSrc(ret.value);
  - returnValue.name = "<return value>";
  }
  nextInstruction = exitingFrame->funcCallInstruction;
  