libswscale/swscale_unscaled.c:1145: error: Null Dereference
  pointer `desc` last assigned on line 1141 could be null and is dereferenced at line 1145, column 21.

libswscale/swscale_unscaled.c:1138:1: start of procedure check_image_pointers()
1136. }
1137. 
1138. static int check_image_pointers(uint8_t *data[4], enum AVPixelFormat pix_fmt,
      ^
1139.                                 const int linesizes[4])
1140. {

libswscale/swscale_unscaled.c:1141:5: 
1139.                                 const int linesizes[4])
1140. {
1141.     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);
          ^
1142.     int i;
1143. 

libavutil/pixdesc.c:1559:1: start of procedure av_pix_fmt_desc_get()
  1557. }
  1558. 
  1559. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1561:9: Taking false branch
  1559. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1562.         return NULL;
  1563.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1561:24: Taking true branch
  1559. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1562.         return NULL;
  1563.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1562:9: 
  1560. {
  1561.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1562.         return NULL;
                ^
  1563.     return &av_pix_fmt_descriptors[pix_fmt];
  1564. }

libavutil/pixdesc.c:1564:1: return from a call to av_pix_fmt_desc_get
  1562.         return NULL;
  1563.     return &av_pix_fmt_descriptors[pix_fmt];
  1564. }
        ^
  1565. 
  1566. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libswscale/swscale_unscaled.c:1144:10: 
1142.     int i;
1143. 
1144.     for (i = 0; i < 4; i++) {
               ^
1145.         int plane = desc->comp[i].plane;
1146.         if (!data[plane] || !linesizes[plane])

libswscale/swscale_unscaled.c:1144:17: Loop condition is true. Entering loop body
1142.     int i;
1143. 
1144.     for (i = 0; i < 4; i++) {
                      ^
1145.         int plane = desc->comp[i].plane;
1146.         if (!data[plane] || !linesizes[plane])

libswscale/swscale_unscaled.c:1145:9: 
1143. 
1144.     for (i = 0; i < 4; i++) {
1145.         int plane = desc->comp[i].plane;
              ^
1146.         if (!data[plane] || !linesizes[plane])
1147.             return 0;
