[ubsan] decode.c:2326:10: runtime error: applying zero offset to null pointer

../../third_party/dav1d/libdav1d/src/decode.c:2326:10: runtime error: applying zero offset to null pointer
    #0 0x555826cb597d in setup_tile third_party/dav1d/libdav1d/src/decode.c:2326:10
    #1 0x555826cb149e in dav1d_decode_frame third_party/dav1d/libdav1d/src/decode.c:2972:13
    #2 0x555826cb8cb1 in dav1d_submit_frame third_party/dav1d/libdav1d/src/decode.c:3489:20
    #3 0x555826c9b514 in dav1d_parse_obus third_party/dav1d/libdav1d/src/obu.c:1548:24
    #4 0x555826c710c7 in dav1d_get_picture third_party/dav1d/libdav1d/src/lib.c:372:15
    #5 0x55582601f70c in media::Dav1dVideoDecoder::DecodeBuffer(scoped_refptr<media::DecoderBuffer>) media/filters/dav1d_video_decoder.cc:326:21

clusterfuzz-testcase-minimized-mediasource_MP4_AV1_pipeline_integration_fuzzer-5744621027983360

Seems to have shown up after the latest drop we picked up: https://chromium-review.googlesource.com/c/chromium/src/+/1928014

But the fuzzer is still figuring out the regression range, so maybe earlier.