libavfilter/vf_pad.c:145: error: Null Dereference
  pointer `pix_desc` last assigned on line 139 could be null and is dereferenced at line 145, column 15.

libavfilter/vf_pad.c:135:1: start of procedure config_input()
133. }
134. 
135. static int config_input(AVFilterLink *inlink)
     ^
136. {
137.     AVFilterContext *ctx = inlink->dst;

libavfilter/vf_pad.c:137:5: 
135. static int config_input(AVFilterLink *inlink)
136. {
137.     AVFilterContext *ctx = inlink->dst;
         ^
138.     PadContext *s = ctx->priv;
139.     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);

libavfilter/vf_pad.c:138:5: 
136. {
137.     AVFilterContext *ctx = inlink->dst;
138.     PadContext *s = ctx->priv;
         ^
139.     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
140.     uint8_t rgba_color[4];

libavfilter/vf_pad.c:139:5: 
137.     AVFilterContext *ctx = inlink->dst;
138.     PadContext *s = ctx->priv;
139.     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
         ^
140.     uint8_t rgba_color[4];
141.     int ret, is_packed_rgba;

libavutil/pixdesc.c:1703:1: start of procedure av_pix_fmt_desc_get()
  1701. }
  1702. 
  1703. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
        ^
  1704. {
  1705.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)

libavutil/pixdesc.c:1705:9: Taking false branch
  1703. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1704. {
  1705.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                ^
  1706.         return NULL;
  1707.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1705:24: Taking true branch
  1703. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
  1704. {
  1705.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
                               ^
  1706.         return NULL;
  1707.     return &av_pix_fmt_descriptors[pix_fmt];

libavutil/pixdesc.c:1706:9: 
  1704. {
  1705.     if (pix_fmt < 0 || pix_fmt >= AV_PIX_FMT_NB)
  1706.         return NULL;
                ^
  1707.     return &av_pix_fmt_descriptors[pix_fmt];
  1708. }

libavutil/pixdesc.c:1708:1: return from a call to av_pix_fmt_desc_get
  1706.         return NULL;
  1707.     return &av_pix_fmt_descriptors[pix_fmt];
  1708. }
        ^
  1709. 
  1710. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev)

libavfilter/vf_pad.c:145:5: 
143.     char *expr;
144. 
145.     s->hsub = pix_desc->log2_chroma_w;
         ^
146.     s->vsub = pix_desc->log2_chroma_h;
147. 
