Segfault in playlist.c in zig-pkg branch

Sorry if its an obvious fix, but I can't seem to find a config issue.
Relevant to the `zig-pkg` branch.
Steps to reproduce:
```
$ zig build
$ ./zig-out/bin/groovebasin
info: music directory: ~/Music
debug: libgroove version: 4.3.0
info: output device: Dummy Output Device
audio queue size: 1
encoder: using codec: libmp3lame MP3 (MPEG audio layer 3)
encoder: using audio format: signed 16-bit LE, 44100 Hz, Stereo
audio queue size: 65536
info: init library
debug: found: ~/Music/music/arch.txt
Segmentation fault at address 0x0
~/.cache/zig/p/1220a0d8f003fda4cd9c3029f04e0a315216f60b2e3343f89fc2248ccd5edfe796fb/src/playlist.c:569:51: 0x811800 in groove_playlist_destroy (~/.cache/zig/p/1220a0d8f003fda4cd9c3029f04e0a315216f60b2e3343f89fc2248ccd5edfe796fb/src/playlist.c)
struct GrooveSink *sink = stack_item->sink;
^
~/projct/imported/groovebasin/src/server/Player.zig:45:28: 0x7066b4 in deinit (groovebasin)
player.playlist.destroy();
^
~/projct/imported/groovebasin/src/server/server_main.zig:135:24: 0x6c7475 in listen (groovebasin)
defer player.deinit();
^
~/projct/imported/groovebasin/src/server/server_main.zig:104:18: 0x6c00dc in main (groovebasin)
return listen(arena, config);
^
/usr/lib/zig/std/start.zig:574:37: 0x6bf05e in main (groovebasin)
const result = root.main() catch |err| {
^
???:?:?: 0x7f734e027ccf in ??? (libc.so.6)
Unwind information for `libc.so.6:0x7f734e027ccf` was not available, trace may be incomplete

Aborted (core dumped)
```