Ensure pack is initialised when loading an asset pack

src/pak.c

@@ -128,6 +128,8 @@ asset_pack_t *load_asset_pack(const char *filepath) {
     return NULL;
   }
 
+  memset((void *)pack, 0, sizeof(asset_pack_t));
+
   pack->fp = fopen(full_path, "rb");
   if (!(pack->fp)) {
     close_asset_pack(&pack);