nutdec: check chapter creation in decode_info_header

This fixes a segmentation fault when accessing the metadata.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 3ff1af2b0db7132d5717be6395227a94c8abab07)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
1 file changed