zellij panics if $TMPDIR is set but does not exist

[acuteaangle]

Basic information

zellij --version:
zellij 0.41.2

stty size:
61 209

uname -av:
Linux [host-redacted] 6.6.63-hardened1 #1-NixOS SMP PREEMPT_DYNAMIC Fri Nov 22 14:38:37 UTC 2024 x86_64 GNU/Linux

Issue description

If $TMPDIR is set, but does not point to a valid directory, zellij will panic.
While an invalid $TMPDIR is obviously a problem of it’s own, I’m assuming that any user-facing panic is considered a bug in zellij.

Minimal reproduction

$ TMPDIR=/nonexistant zellij
thread 'main' panicked at zellij-utils/src/logging.rs:27:41:
called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" }
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

$ TMPDIR=/nonexistant RUST_BACKTRACE=full zellij
thread 'main' panicked at zellij-utils/src/logging.rs:27:41:
called `Result::unwrap()` on an `Err` value: Os { code: 2, kind: NotFound, message: "No such file or directory" }
stack backtrace:
   0:      0xfb51e7241e7 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h9754a6437f1de22a
   1:      0xfb51e3dcd4b - core::fmt::write::hb706a393bb60a06f
   2:      0xfb51e7277be - std::io::Write::write_fmt::h9b447dc5d824d0bd
   3:      0xfb51e75a512 - std::panicking::default_hook::{{closure}}::h227952daede9dd84
   4:      0xfb51e75b413 - std::panicking::rust_panic_with_hook::h76d2aa694a00748e
   5:      0xfb51e724655 - std::panicking::begin_panic_handler::{{closure}}::h8855a344ffa1638b
   6:      0xfb51e7245b9 - std::sys::backtrace::__rust_end_short_backtrace::h3110d0cbfbf26886
   7:      0xfb51e75a9c4 - rust_begin_unwind
   8:      0xfb51e25b4b2 - core::panicking::panic_fmt::h3af706d0346c1c60
   9:      0xfb51e25af85 - core::result::unwrap_failed::h2ba69a02b8a8418b
  10:      0xfb51f1b814b - zellij_utils::logging::configure_logger::hba89da7fca914cc1
  11:      0xfb51ea86914 - zellij::main::hd92f5a111822d18b
  12:      0xfb51eaaab83 - std::sys::backtrace::__rust_begin_short_backtrace::h7bfcb6dd8cf0116b
  13:      0xfb51ea866da - main
  14:     0x647cd617727e - __libc_start_call_main
  15:     0x647cd6177339 - __libc_start_main_alias_2
  16:      0xfb51e2d7915 - _start
  17:                0x0 - <unknown>

---

(For anyone interested in how this actually happened, I ran nix-shell -p cosmic-term --run cosmic-term to try the alpha cosmic-term. nix-shell creates a dedicated subdir of /tmp as $TMPDIR for each shell it launches, but cosmic-term immediately detaches from the shell, which then exits and the subdir gets cleaned up automatically. I then tried to run zellij in the new cosmic-term window.)