Obtained 22 stack frames.
/usr/games/crawl-git-18991dcc64(_Z17write_stack_traceP8_IO_FILE+0x3f) [0x5c4870dd6c4f]: write_stack_trace(_IO_FILE*)
/usr/games/crawl-git-18991dcc64(_Z20crash_signal_handleri+0x196) [0x5c4870dd70e6]: crash_signal_handler(int)
/lib/x86_64-linux-gnu/libc.so.6(+0x45330) [0x7eaf8abd7330]: 
/usr/games/crawl-git-18991dcc64(_Z12dgn_vault_at9coord_def+0x42) [0x5c4870e9c172]: dgn_vault_at(coord_def)
/usr/games/crawl-git-18991dcc64(_Z23raw_feature_descriptionB5cxx11RK9coord_def+0x55) [0x5c4870e7c145]: raw_feature_description[abi:cxx11](coord_def const&)
/usr/games/crawl-git-18991dcc64(_Z13do_crash_dumpv+0x2237) [0x5c4870de6ca7]: do_crash_dump()
/usr/games/crawl-git-18991dcc64(_Z20crash_signal_handleri+0x1fa) [0x5c4870dd714a]: crash_signal_handler(int)
/lib/x86_64-linux-gnu/libc.so.6(+0x45330) [0x7eaf8abd7330]: 
/lib/x86_64-linux-gnu/libc.so.6(pthread_kill+0x11c) [0x7eaf8ac30b2c]: 
/lib/x86_64-linux-gnu/libc.so.6(gsignal+0x1e) [0x7eaf8abd727e]: 
/usr/games/crawl-git-18991dcc64(+0x55427d) [0x5c4870de427d]: 
/usr/games/crawl-git-18991dcc64(_Z12AssertFailedPKcS0_iS0_z+0x1c7) [0x5c4870de4787]: AssertFailed(char const*, char const*, int, char const*, ...)
/usr/games/crawl-git-18991dcc64(_Z9save_gamebPKc+0x7c4) [0x5c4870ef14c4]: save_game(bool, char const*)
/usr/games/crawl-git-18991dcc64(_Z21check_selected_skillsv+0x257) [0x5c487139cce7]: check_selected_skills()
/usr/games/crawl-git-18991dcc64(+0x65f915) [0x5c4870eef915]: 
/usr/games/crawl-git-18991dcc64(_Z12restore_gameRKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE+0x23) [0x5c4870ef0443]: restore_game(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)
/usr/games/crawl-git-18991dcc64(_Z12startup_stepv+0x947) [0x5c4871436cf7]: startup_step()
/usr/games/crawl-git-18991dcc64(+0xd3244d) [0x5c48715c244d]: 
/usr/games/crawl-git-18991dcc64(main+0x1f7) [0x5c4870d084e7]: 
/lib/x86_64-linux-gnu/libc.so.6(+0x2a1ca) [0x7eaf8abbc1ca]: 
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x8b) [0x7eaf8abbc28b]: 
/usr/games/crawl-git-18991dcc64(_start+0x25) [0x5c4870d08fd5]: