Bug: panicked at 'called `Option::unwrap()` on a `None` value'

I dont know which operation exactly it is, but I keep getting this error(gcsf needs to be restarted after this):

```
INFO gcsf::gcsf::file_manager > Checking for changes and possibly applying them.
thread '' panicked at 'called `Option::unwrap()` on a `None` value', src/libcore/option.rs:355:21
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
stack backtrace:
0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
at src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
1: std::sys_common::backtrace::_print
at src/libstd/sys_common/backtrace.rs:71
2: std::panicking::default_hook::{{closure}}
at src/libstd/sys_common/backtrace.rs:59
at src/libstd/panicking.rs:211
3: std::panicking::default_hook
at src/libstd/panicking.rs:227
4: std::panicking::rust_panic_with_hook
at src/libstd/panicking.rs:491
5: std::panicking::continue_panic_fmt
at src/libstd/panicking.rs:398
6: rust_begin_unwind
at src/libstd/panicking.rs:325
7: core::panicking::panic_fmt
at src/libcore/panicking.rs:95
8: core::panicking::panic
at src/libcore/panicking.rs:59
9: >::unwrap
at /rustc/9fda7c2237db910e41d6a712e9a2139b352e558b/src/libcore/macros.rs:20
10: gcsf::gcsf::file_manager::FileManager::get_node_id
at src/gcsf/file_manager.rs:291
11: gcsf::gcsf::file_manager::FileManager::add_file_locally
at src/gcsf/file_manager.rs:372
12: gcsf::gcsf::file_manager::FileManager::sync
at src/gcsf/file_manager.rs:129
13: ::readdir
at src/gcsf/filesystem.rs:179
14: fuse::request::Request::dispatch
at /root/.cargo/registry/src/github.com-1ecc6299db9ec823/fuse-0.3.1/src/request.rs:311
15: fuse::request::dispatch
at /root/.cargo/registry/src/github.com-1ecc6299db9ec823/fuse-0.3.1/src/request.rs:34
16: >::run
at /root/.cargo/registry/src/github.com-1ecc6299db9ec823/fuse-0.3.1/src/session.rs:79
17: fuse::session::BackgroundSession::new::{{closure}}
at /root/.cargo/registry/src/github.com-1ecc6299db9ec823/fuse-0.3.1/src/session.rs:130
18: thread_scoped::scoped::{{closure}}
at /root/.cargo/registry/src/github.com-1ecc6299db9ec823/thread-scoped-1.0.2/src/lib.rs:76
WARN fuse::reply > Reply not sent for operation 2235356, replying with I/O error
```

I will try to get the verbose backtrace soon :)