Update: For me the error disappeared after a simple reboot.
After installation I could the tool get running only after installing the package gir1.2-ayatanaappindicator3-0.1 (see my report https://bugs.launchpad.net/ubuntu/+source/ayatana-webmail/+bug/1972089). Maybe after doing that a reboot would have been necessary in order to get it run smoothly.
Update: For me the error disappeared after a simple reboot. ayatanaappindic ator3-0. 1 (see my report https:/ /bugs.launchpad .net/ubuntu/ +source/ ayatana- webmail/ +bug/1972089). Maybe after doing that a reboot would have been necessary in order to get it run smoothly.
After installation I could the tool get running only after installing the package gir1.2-