libavfilter/vf_overlay.c:108: error: Null Dereference
  pointer `pix_desc` last assigned on line 105 could be null and is dereferenced at line 108, column 15.

libavfilter/vf_overlay.c:102:1: start of procedure config_input_main()
100. }
101. 
102. static int config_input_main(AVFilterLink *inlink)
     ^
103. {
104.     OverlayContext *s = inlink->dst->priv;

libavfilter/vf_overlay.c:104:5: 
102. static int config_input_main(AVFilterLink *inlink)
103. {
104.     OverlayContext *s = inlink->dst->priv;
         ^
105.     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
106. 

libavfilter/vf_overlay.c:105:5: 
103. {
104.     OverlayContext *s = inlink->dst->priv;
105.     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
         ^
106. 
107.     av_image_fill_max_pixsteps(s->max_plane_step, NULL, pix_desc);

libavutil/pixdesc.c:1464:1: start of procedure av_pix_fmt_desc_get()
  1462. }
  1463. 
  1464. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1466:9: Taking false branch
  1464. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1467.         return NULL;
  1468.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1466:24: Taking true branch
  1464. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1467.         return NULL;
  1468.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1467:9: 
  1465. {
  1466.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1467.         return NULL;
                ^
  1468.     return &av_pix_fmt_descriptors[pix_fmt];
  1469. }

libavutil/pixdesc.c:1469:1: return from a call to av_pix_fmt_desc_get
  1467.         return NULL;
  1468.     return &av_pix_fmt_descriptors[pix_fmt];
  1469. }
        ^
  1470. 
  1471. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavfilter/vf_overlay.c:107:5: Skipping av_image_fill_max_pixsteps(): empty list of specs
105.     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
106. 
107.     av_image_fill_max_pixsteps(s->max_plane_step, NULL, pix_desc);
         ^
108.     s->hsub = pix_desc->log2_chroma_w;
109.     s->vsub = pix_desc->log2_chroma_h;

libavfilter/vf_overlay.c:108:5: 
106. 
107.     av_image_fill_max_pixsteps(s->max_plane_step, NULL, pix_desc);
108.     s->hsub = pix_desc->log2_chroma_w;
         ^
109.     s->vsub = pix_desc->log2_chroma_h;
110. 
