Error codes
GQuark flatpak_error_quark (void);
void
#define FLATPAK_ERROR flatpak_error_quark ()
Error codes for library functions.
FLATPAK_ERROR_ALREADY_INSTALLED
App/runtime is already installed
FLATPAK_ERROR_NOT_INSTALLED
App/runtime is not installed
FLATPAK_ERROR_ONLY_PULLED
App/runtime was only pulled into the local repository but not installed.