The same error message appears for me on Ubuntu 16.04 and hplib 3.16.3 when calling hp-setup -i without sudo.
When I call it with sudo everything runs fine but a warning appears that it should *not* be called in a root mode (warning: It is not recommended to run 'hp-plugin' in a root mode).
So I guess calling it with sudo is a workaround but not the correct one.
The same error message appears for me on Ubuntu 16.04 and hplib 3.16.3 when calling hp-setup -i without sudo.
When I call it with sudo everything runs fine but a warning appears that it should *not* be called in a root mode (warning: It is not recommended to run 'hp-plugin' in a root mode).
So I guess calling it with sudo is a workaround but not the correct one.