electimon [1] filed a deletion request for echo-icon-theme [2]:

This icon theme was last updated in 2010, the upstream url does not work and the new upstream url (https://pagure.io/echo-project/) holds outdated releases. Version '0.3.89.0' appears to be the latest but upstream does not have it. echo-icon-theme-git builds and installs fine so users should use that instead.

[1] https://aur.archlinux.org/account/electimon/ [2] https://aur.archlinux.org/pkgbase/echo-icon-theme/