demux: mp4: add missing vlc_input_attachment_New() error handling

modules/demux/mp4/mp4.c

@@ -1586,8 +1586,14 @@ static int Control( demux_t *p_demux, int i_query, va_list args )
                     char rgsz_location[12];
                     snprintf( rgsz_location, 12, "%4.4s[%"PRIu16"]", (char*)&rgi_pict_atoms[i],
                               (uint16_t) i_box_count - 1 );
-                    (*ppp_attach)[i_count++] = vlc_input_attachment_New( rgsz_location, "image/x-pict",
+                    (*ppp_attach)[i_count] = vlc_input_attachment_New( rgsz_location, "image/x-pict",
                         "Quickdraw image", p_pict->data.p_binary->p_blob, p_pict->data.p_binary->i_blob );
+                    if ( !(*ppp_attach)[i_count] )
+                    {
+                        i_count = 0;
+                        break;
+                    }
+                    i_count++;
                     msg_Dbg( p_demux, "adding attachment %s", rgsz_location );
                 }
             }