fix null pointer dereference in stb_image.h

src/stb_image.c

@@ -5408,7 +5408,7 @@ static stbi_uc *stbi__pic_load(stbi__context *s,int *px,int *py,int *comp,int re
 
    if (!stbi__pic_load_core(s,x,y,comp, result)) {
       STBI_FREE(result);
-      result=0;
+      return 0;
    }
    *px = x;
    *py = y;