Can you please try if the error goes away by copying another icon over the presumably corrupted `/usr/share/stream2ip-gtk3/icons/S2-setup.svg' (rename the S2-setup.svg first to be able to restore it) - this would then tell us that it is the .svg file which is corrupted.
I do appreciate your help very much!
Can you please try if the error goes away by copying another icon over the presumably corrupted `/usr/share/ stream2ip- gtk3/icons/ S2-setup. svg' (rename the S2-setup.svg first to be able to restore it) - this would then tell us that it is the .svg file which is corrupted.