This is some noise due to the (default) invitation handling. Each time the calendar storage is opened (here by the event view calendar widget or more accurate by the daemon providing calendar resource to the widget), there is a check done to get the associated email address of the calendar. If there is no email address (perfectly valid case), it is warning (useless noise).
For more details:
- the warning message is defined in
- the call comes from
nemo-qml-plugin-calendar/src/calendarworker.cpp when listing all calendars in storage on opening, see
notebook.emailAddress = mKCal::ServiceHandler::instance().emailAddress(mkNotebook, mStorage);
- the third line is also some noise from the default invitation plugin, since the calendar is not storing any email address, it is then poking the email messaging daemon to get the default email account. And for whatever reason, it is returning none of them.
This is not really a sign of issue except if you plan to send calendar invitations. But you should use an account that support it, like EAS or CalDAV one. And in that case, the noisy default invitation plugin will not be used anyway.
Creating a PR to minimise the noise could be a good idea ; )