libswscale/swscale_unscaled.c:1031: error: Null Dereference
  pointer `desc` last assigned on line 1027 could be null and is dereferenced at line 1031, column 21.

libswscale/swscale_unscaled.c:1024:1: start of procedure check_image_pointers()
1022. }
1023. 
1024. static int check_image_pointers(uint8_t *data[4], enum AVPixelFormat pix_fmt,
      ^
1025.                                 const int linesizes[4])
1026. {

libswscale/swscale_unscaled.c:1027:5: 
1025.                                 const int linesizes[4])
1026. {
1027.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);
          ^
1028.     int i;
1029. 

libavutil/pixdesc.c:1433:1: start of procedure av_pix_fmt_desc_get()
  1431. }
  1432. 
  1433. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1434. {
  1435.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1435:9: Taking false branch
  1433. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1434. {
  1435.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1436.         return NULL;
  1437.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1435:24: Taking true branch
  1433. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1434. {
  1435.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1436.         return NULL;
  1437.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1436:9: 
  1434. {
  1435.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1436.         return NULL;
                ^
  1437.     return &av_pix_fmt_descriptors[pix_fmt];
  1438. }

libavutil/pixdesc.c:1438:1: return from a call to av_pix_fmt_desc_get
  1436.         return NULL;
  1437.     return &av_pix_fmt_descriptors[pix_fmt];
  1438. }
        ^
  1439. 
  1440. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libswscale/swscale_unscaled.c:1030:10: 
1028.     int i;
1029. 
1030.     for (i = 0; i < 4; i++) {
               ^
1031.         int plane = desc->comp[i].plane;
1032.         if (!data[plane] || !linesizes[plane])

libswscale/swscale_unscaled.c:1030:17: Loop condition is true. Entering loop body
1028.     int i;
1029. 
1030.     for (i = 0; i < 4; i++) {
                      ^
1031.         int plane = desc->comp[i].plane;
1032.         if (!data[plane] || !linesizes[plane])

libswscale/swscale_unscaled.c:1031:9: 
1029. 
1030.     for (i = 0; i < 4; i++) {
1031.         int plane = desc->comp[i].plane;
              ^
1032.         if (!data[plane] || !linesizes[plane])
1033.             return 0;
