`erd --long` crashes when attempting to display user/group info for nonexistant group/user

[nwoythal]

I have a file on my filesystem that is owned by a GID that doesn't exist locally (but does inside a container) -- when erd attempts to fetch the data from this file, a SIGSEGV is generated:

$ touch foo
$ sudo chown :9999 foo
$ ls -plaht foo
-rw-rw-r-- 1 natewo 9999 0 Jun  7 11:54 foo
$ erd --no-config --long foo
[1]    1025586 segmentation fault (core dumped)  erd foo
$ sudo chown 9999:natewo foo
$ ls -plaht foo
-rw-rw-r-- 1 9999 natewo 0 Jun  7 11:54 foo
$ erd --no-config --long foo
[1]    1025644 segmentation fault (core dumped)  erd fo

FWIW I know very little about rust, but it seems to be coming from src/fs/ug.rs:try_get_user/src/fs/ug.rs:try_get_group