The index.theme file for the breeze icon theme is apparently in the category of desktop entry files which are treated as executable even though they might not have executable permissions. When the index.theme file is (double) clicked, it's opened by the default text editor (because it doesn't contain "Type=Application"), but it also results in an unwanted error sound and an error message complaining that there is no "Type=..." entry. It seems a solution for this could be inserting the following two lines to index.theme file: [Desktop Entry] Type=Icon Theme Actually, it might look better if the line "Type=Icon Theme" could replace the following line, i.e. "[Icon Theme], if it doesn't require too many changes elsewhere.
The problem is that kio thinks its a desktop file even if it's not. It's not a desktop entry so shouldn't have one. See also https://specifications.freedesktop.org/icon-theme-spec/icon-theme-spec-latest.html Reproduce with kioclient5 exec index.theme
A possibly relevant merge request was started @ https://invent.kde.org/frameworks/kio/-/merge_requests/383
Git commit ed89a0ac03a3ed5c7ca98c37a2b8acb1d10ac514 by David Redondo. Committed on 31/03/2021 at 12:09. Pushed by ahmadsamir into branch 'master'. Handle .theme files correctly Even though they are desktop files they do not have a Type entry. M +2 -2 src/gui/openurljob.cpp https://invent.kde.org/frameworks/kio/commit/ed89a0ac03a3ed5c7ca98c37a2b8acb1d10ac514