Bypass overlay frame tpl stats processing

Resolve runtime errors in debug mode.

Change-Id: Ib67c89c8dd5a5a092580688108e68850650ea94b
diff --git a/av1/ratectrl_qmode.cc b/av1/ratectrl_qmode.cc
index 02824d3..e973708 100644
--- a/av1/ratectrl_qmode.cc
+++ b/av1/ratectrl_qmode.cc
@@ -908,6 +908,9 @@
 
 TplFrameDepStats CreateTplFrameDepStatsWithoutPropagation(
     const TplFrameStats &frame_stats) {
+  if (frame_stats.block_stats_list.empty()) {
+    return {};
+  }
   const int min_block_size = frame_stats.min_block_size;
   TplFrameDepStats frame_dep_stats = CreateTplFrameDepStats(
       frame_stats.frame_height, frame_stats.frame_width, min_block_size);
@@ -1004,6 +1007,8 @@
   TplFrameDepStats *frame_dep_stats =
       &tpl_gop_dep_stats->frame_dep_stats_list[coding_idx];
 
+  if (frame_dep_stats->unit_stats.empty()) return;
+
   const int unit_size = frame_dep_stats->unit_size;
   const int frame_unit_rows =
       static_cast<int>(frame_dep_stats->unit_stats.size());