The background with the ID 1271777873 doesn't seem to work. It seems to have a different folder structure than what is expected
Console output
ferdmusic linux-wallpaperengine 1271777873
[1006/162044.486772:WARNING:resource_util.cc(94)] Please customize CefSettings.root_cache_path for your application. Use of the default value may lead to unintended process singleton behavior.
No "scene.pkg" file found at "/home/ferdmusic/.var/app/com.valvesoftware.Steam/.local/share/Steam/steamapps/workshop/content/431960/1271777873/scene.pkg". Defaulting to normal folder storage
No "gifscene.pkg" file found at "/home/ferdmusic/.var/app/com.valvesoftware.Steam/.local/share/Steam/steamapps/workshop/content/431960/1271777873/gifscene.pkg". Defaulting to normal folder storage
WARNING: Shader patches directory cannot be found, this might make some backgrounds not work properly
terminate called after throwing an instance of 'nlohmann::detail::type_error'
what(): [json.exception.type_error.302] type must be string, but is number
MESA-LOADER: failed to open nvidia-drm: /usr/lib/gbm/nvidia-drm_gbm.so: Kann die Shared-Object-Datei nicht öffnen: Datei oder Verzeichnis nicht gefunden (search paths /usr/lib/gbm, suffix _gbm)
[0100/000000.839629:WARNING:sandbox_linux.cc(400)] InitializeSandbox() called with multiple threads in process gpu-process.
/usr/bin/linux-wallpaperengine: Zeile 2: 620730 Abgebrochen (Speicherabzug geschrieben) ./linux-wallpaperengine $*
ls /home/ferdmusic/.var/app/com.valvesoftware.Steam/.local/share/Steam/steamapps/workshop/content/431960/1271777873/
audio imgs index.html js map preview.jpg preview.png project.json style video video.webm
Take a look at your project.json file, check if there's a Type parameter and it has to be a string; from the look of your error log, it seems it's a number at the moment.
Wallpaper Engine Background(s)
The background with the ID 1271777873 doesn't seem to work. It seems to have a different folder structure than what is expected
Console output
Desktop