libavfilter/vf_overlay.c:119: error: Null Dereference
  pointer `pix_desc` last assigned on line 116 could be null and is dereferenced at line 119, column 18.

libavfilter/vf_overlay.c:113:1: start of procedure config_input_main()
111. }
112. 
113. static int config_input_main(AVFilterLink *inlink)
     ^
114. {
115.     OverlayContext *over = inlink->dst->priv;

libavfilter/vf_overlay.c:115:5: 
113. static int config_input_main(AVFilterLink *inlink)
114. {
115.     OverlayContext *over = inlink->dst->priv;
         ^
116.     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
117. 

libavfilter/vf_overlay.c:116:5: 
114. {
115.     OverlayContext *over = inlink->dst->priv;
116.     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
         ^
117. 
118.     av_image_fill_max_pixsteps(over->max_plane_step, NULL, pix_desc);

libavutil/pixdesc.c:1199:1: start of procedure av_pix_fmt_desc_get()
  1197. }
  1198. 
  1199. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1200. {
  1201.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1201:9: Taking false branch
  1199. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1200. {
  1201.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1202.         return NULL;
  1203.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1201:24: Taking true branch
  1199. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1200. {
  1201.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1202.         return NULL;
  1203.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1202:9: 
  1200. {
  1201.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1202.         return NULL;
                ^
  1203.     return &av_pix_fmt_descriptors[pix_fmt];
  1204. }

libavutil/pixdesc.c:1204:1: return from a call to av_pix_fmt_desc_get
  1202.         return NULL;
  1203.     return &av_pix_fmt_descriptors[pix_fmt];
  1204. }
        ^
  1205. 
  1206. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavfilter/vf_overlay.c:118:5: Skipping av_image_fill_max_pixsteps(): empty list of specs
116.     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
117. 
118.     av_image_fill_max_pixsteps(over->max_plane_step, NULL, pix_desc);
         ^
119.     over->hsub = pix_desc->log2_chroma_w;
120.     over->vsub = pix_desc->log2_chroma_h;

libavfilter/vf_overlay.c:119:5: 
117. 
118.     av_image_fill_max_pixsteps(over->max_plane_step, NULL, pix_desc);
119.     over->hsub = pix_desc->log2_chroma_w;
         ^
120.     over->vsub = pix_desc->log2_chroma_h;
121. 
