Issue Summary

When trying to add a CalDAV service on my account on the official instance (calendso.com), I get the message "Error: Could not add this caldav account". It would be nicer to have a more explicit error message.
The credentials I supply to Calendso work fine when used via Thunderbird/Lightning.
The CalDAV server is a Baikal 0.8.0 instance (https://sabre.io/baikal/).

Steps to Reproduce

1. (for example) Went to https://app.calendso.com/getting-started
2. Clicked on "Caldav"
3. Filled in my CalDAV URL and credentials.
4. Get the error message

Any other relevant information. For example, why do you consider this a bug and what did you expect to happen instead?

Technical details

• Browser version: Firefox ESR
• Node.js version - don't know