libavfilter/vf_unsharp.c:178: error: Null Dereference
  pointer `desc` last assigned on line 176 could be null and is dereferenced at line 178, column 21.

libavfilter/vf_unsharp.c:173:1: start of procedure config_props()
171. }
172. 
173. static int config_props(AVFilterLink *link)
     ^
174. {
175.     UnsharpContext *unsharp = link->dst->priv;

libavfilter/vf_unsharp.c:175:5: 
173. static int config_props(AVFilterLink *link)
174. {
175.     UnsharpContext *unsharp = link->dst->priv;
         ^
176.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
177. 

libavfilter/vf_unsharp.c:176:5: 
174. {
175.     UnsharpContext *unsharp = link->dst->priv;
176.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
         ^
177. 
178.     unsharp->hsub = desc->log2_chroma_w;

libavutil/pixdesc.c:1685:1: start of procedure av_pix_fmt_desc_get()
  1683. }
  1684. 
  1685. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1686. {
  1687.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1687:9: Taking false branch
  1685. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1686. {
  1687.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1688.         return NULL;
  1689.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1687:24: Taking true branch
  1685. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1686. {
  1687.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1688.         return NULL;
  1689.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1688:9: 
  1686. {
  1687.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1688.         return NULL;
                ^
  1689.     return &av_pix_fmt_descriptors[pix_fmt];
  1690. }

libavutil/pixdesc.c:1690:1: return from a call to av_pix_fmt_desc_get
  1688.         return NULL;
  1689.     return &av_pix_fmt_descriptors[pix_fmt];
  1690. }
        ^
  1691. 
  1692. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavfilter/vf_unsharp.c:178:5: 
176.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
177. 
178.     unsharp->hsub = desc->log2_chroma_w;
         ^
179.     unsharp->vsub = desc->log2_chroma_h;
180. 
