Container cannot find config.json

[LksBrlt]

Describe the bug

I set up watchtower to update an image from a private registry with the documentation from https://containrrr.dev/watchtower/private-registries/
When mounting the config.json as it is documented, the container starts, but does not scan any images. The debug logging shows the followeing:
"No credentials for : found" config_file=/config/config.json

It is therefore looking for the config file in /config/config.json but in the documentation it should be mounted like this:
- <PATH_TO_HOME_DIR>/.docker/config.json:/config.json

Steps to reproduce

1. Create config.json in <PATH_TO_HOME_DIR>/.docker/config.json
2. In compose.yaml file set
   • <PATH_TO_HOME_DIR>/.docker/config.json:/config.json
3. make docker-compose up -d
4. See error:
   "No credentials for : found" config_file=/config/config.json
5. See logging:
   level=info msg="Session done" Failed=0 Scanned=0 Updated=0 notify=no

Expected behavior

It should find the config.json and be able to authenticate. When mounting it like this:
<PATH_TO_HOME_DIR>/.docker/config.json:/config/config.json it works

Screenshots

No response

Environment

• Linux
• x86_64
• 27.4.1-ce

Your logs

"No credentials for : found" config_file=/config/config.json

Additional context

No response

[github-actions]

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