libavfilter/vf_scale.c:265: error: Null Dereference
  pointer `desc` last assigned on line 260 could be null and is dereferenced at line 265, column 19.

libavfilter/vf_scale.c:255:1: start of procedure filter_frame()
253. }
254. 
255. static int filter_frame(AVFilterLink *link, AVFrame *in)
     ^
256. {
257.     ScaleContext *scale = link->dst->priv;

libavfilter/vf_scale.c:257:5: 
255. static int filter_frame(AVFilterLink *link, AVFrame *in)
256. {
257.     ScaleContext *scale = link->dst->priv;
         ^
258.     AVFilterLink *outlink = link->dst->outputs[0];
259.     AVFrame *out;

libavfilter/vf_scale.c:258:5: 
256. {
257.     ScaleContext *scale = link->dst->priv;
258.     AVFilterLink *outlink = link->dst->outputs[0];
         ^
259.     AVFrame *out;
260.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);

libavfilter/vf_scale.c:260:5: 
258.     AVFilterLink *outlink = link->dst->outputs[0];
259.     AVFrame *out;
260.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
         ^
261. 
262.     if (!scale->sws)

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_scale.c:262:10: Taking false branch
260.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
261. 
262.     if (!scale->sws)
              ^
263.         return ff_filter_frame(outlink, in);
264. 

libavfilter/vf_scale.c:265:5: 
263.         return ff_filter_frame(outlink, in);
264. 
265.     scale->hsub = desc->log2_chroma_w;
         ^
266.     scale->vsub = desc->log2_chroma_h;
267. 
