[BUG] Cannot run sync twice on TW<->CalDAV

[RaitoBezarius]

Describe the bug

On second restart of synchronization, I get a crash with the following trace: https://gist.github.com/RaitoBezarius/4af81a60c5736dbabc44b71e975b9ebe

To Reproduce

I run the following script:

#!/nix/store/vqvj60h076bhqj6977caz0pfxs6543nb-bash-5.2-p15/bin/bash
set -o errexit
set -o nounset
set -o pipefail

export PATH="/nix/store/iz4dlydb7paz2f8xi0dfk6kfdmhm7d4c-gnupg-2.4.1/bin:$PATH"

export TASKRC=/home/raito/.config/task/taskrc
/nix/store/5kwpflid12cs3gxdc8vzg7sdgdw8826k-syncall-1.5.1/bin/tw_caldav_sync \
  --caldav-calendar TODO \
  --caldav-url https://redacted/remote.php/dav \
  --caldav-user raito \
  --caldav-passwd-pass-path /nix/store/qzy8q7j8ig8086pkbjszh6x0kxg3qzdl-kachpass/bin/kachpass \
  --caldav-passwd Private/nextCloud/twsync \
  --resolution-strategy MostRecentRS \
  --taskwarrior-tags sync-caldav \

twice.

kachpass is just a sophisticated pass interface with caching with kernel keyring.

Expected Behavior

The second time it should also work and continue sync.

📸 Screenshots

If applicable, add screenshots to help explain your problem.

Versions

OS Version (cat /etc/*-release; uname -a)

NixOS 23.11pre526036.3b1f3712a415 (Tapir).

Python version (python --version; python3 --version)

3.10.12

--version of your executable

tw_caldav_sync, version 1.5.1

(I am the packager of syncall in nixpkgs.)

Additional context

Contents of the YAML:

❯ cat ~/.config/syncall/TODO__None__sync-caldav__False__False.yaml
Tw_caldav_ids: !!python/object/apply:bidict._base._from_other
- !!python/name:bidict.bidict ''
- {}
- false

[bergercookie]

Hi @RaitoBezarius sorry for the delay and thanks for shipping this tool to NixOS :)

This looks like an issue with PyYAML, not with syncall or bubop per se.
Could you dump the list of python packages and their versions ? e.g., with pip3 freeze