TypeError: Cannot read property 'map' of undefined

[clochix]

Seen in user logs:

/usr/local/cozy/apps/sync/node_modules/cozy-jsdav-fork/lib/CalDAV/userCalendars.js:143
            var objs = calendars.map(function(calendar) {
                                ^
TypeError: Cannot read property 'map' of undefined
    at /usr/local/cozy/apps/sync/node_modules/cozy-jsdav-fork/lib/CalDAV/userCalendars.js:143:33
    at null._onTimeout (/usr/local/cozy/apps/sync/build/server/backends/caldav.js:81:18)
    at Timer.listOnTimeout (timers.js:92:15)