libavfilter/vf_scale.c:272: error: Null Dereference
  pointer `desc` last assigned on line 267 could be null and is dereferenced at line 272, column 19.

libavfilter/vf_scale.c:262:1: start of procedure filter_frame()
260. }
261. 
262. static int filter_frame(AVFilterLink *link, AVFrame *in)
     ^
263. {
264.     ScaleContext *scale = link->dst->priv;

libavfilter/vf_scale.c:264:5: 
262. static int filter_frame(AVFilterLink *link, AVFrame *in)
263. {
264.     ScaleContext *scale = link->dst->priv;
         ^
265.     AVFilterLink *outlink = link->dst->outputs[0];
266.     AVFrame *out;

libavfilter/vf_scale.c:265:5: 
263. {
264.     ScaleContext *scale = link->dst->priv;
265.     AVFilterLink *outlink = link->dst->outputs[0];
         ^
266.     AVFrame *out;
267.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);

libavfilter/vf_scale.c:267:5: 
265.     AVFilterLink *outlink = link->dst->outputs[0];
266.     AVFrame *out;
267.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
         ^
268. 
269.     if (!scale->sws)

libavutil/pixdesc.c:1574:1: start of procedure av_pix_fmt_desc_get()
  1572. }
  1573. 
  1574. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1575. {
  1576.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1576:9: Taking false branch
  1574. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1575. {
  1576.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1577.         return NULL;
  1578.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1576:24: Taking true branch
  1574. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1575. {
  1576.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1577.         return NULL;
  1578.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1577:9: 
  1575. {
  1576.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1577.         return NULL;
                ^
  1578.     return &av_pix_fmt_descriptors[pix_fmt];
  1579. }

libavutil/pixdesc.c:1579:1: return from a call to av_pix_fmt_desc_get
  1577.         return NULL;
  1578.     return &av_pix_fmt_descriptors[pix_fmt];
  1579. }
        ^
  1580. 
  1581. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavfilter/vf_scale.c:269:10: Taking false branch
267.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
268. 
269.     if (!scale->sws)
              ^
270.         return ff_filter_frame(outlink, in);
271. 

libavfilter/vf_scale.c:272:5: 
270.         return ff_filter_frame(outlink, in);
271. 
272.     scale->hsub = desc->log2_chroma_w;
         ^
273.     scale->vsub = desc->log2_chroma_h;
274. 
