[Plugin: easyReservations] Certain settings cannot be configured

When activating wp debug we received a lot of notices (not so bad) but also errors.
Has some very nice features yet we could not use it due to the errors it throws. Reservations for example did not show up in reservation calendar, yet e-mails are properly sent.
Also a draw back the documentation is not sufficient.
Inserting a reservation required fields are not present – we actually had to check the db to find which fields were missing to complete a manual reservation, which also did not show up in the reservation table due to a date error (second: long expected)

https://www.ads-software.com/extend/plugins/easyreservations/