libswscale/swscale_unscaled.c:1192: error: Null Dereference
  pointer `desc` last assigned on line 1188 could be null and is dereferenced at line 1192, column 21.

libswscale/swscale_unscaled.c:1185:1: start of procedure check_image_pointers()
1183. }
1184. 
1185. static int check_image_pointers(uint8_t *data[4], enum AVPixelFormat pix_fmt,
      ^
1186.                                 const int linesizes[4])
1187. {

libswscale/swscale_unscaled.c:1188:5: 
1186.                                 const int linesizes[4])
1187. {
1188.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);
          ^
1189.     int i;
1190. 

libavutil/pixdesc.c:1768:1: start of procedure av_pix_fmt_desc_get()
  1766. }
  1767. 
  1768. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1769. {
  1770.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1770:9: Taking false branch
  1768. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1769. {
  1770.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1771.         return NULL;
  1772.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1770:24: Taking true branch
  1768. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1769. {
  1770.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1771.         return NULL;
  1772.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1771:9: 
  1769. {
  1770.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1771.         return NULL;
                ^
  1772.     return &av_pix_fmt_descriptors[pix_fmt];
  1773. }

libavutil/pixdesc.c:1773:1: return from a call to av_pix_fmt_desc_get
  1771.         return NULL;
  1772.     return &av_pix_fmt_descriptors[pix_fmt];
  1773. }
        ^
  1774. 
  1775. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libswscale/swscale_unscaled.c:1191:10: 
1189.     int i;
1190. 
1191.     for (i = 0; i < 4; i++) {
               ^
1192.         int plane = desc->comp[i].plane;
1193.         if (!data[plane] || !linesizes[plane])

libswscale/swscale_unscaled.c:1191:17: Loop condition is true. Entering loop body
1189.     int i;
1190. 
1191.     for (i = 0; i < 4; i++) {
                      ^
1192.         int plane = desc->comp[i].plane;
1193.         if (!data[plane] || !linesizes[plane])

libswscale/swscale_unscaled.c:1192:9: 
1190. 
1191.     for (i = 0; i < 4; i++) {
1192.         int plane = desc->comp[i].plane;
              ^
1193.         if (!data[plane] || !linesizes[plane])
1194.             return 0;
