Install gir1.2-gucharmap-2.90 by entering the following commands in the terminal:
sudo apt update sudo apt install gir1.2-gucharmap-2.90
Description:
GObject introspection data for the Unicode browser widget library
The libgucharmap library contains a Unicode browser widget; it is most prominently used by the "gucharmap" program. See the package of the same name for more information. . This package contains introspection data for the Unicode browser widget library.
Homepage: https://wiki.gnome.org/Apps/Gucharmap
Version: 1:10.0.4-1
Section: universe/introspection