Hello @mosleh
I was able to reproduce your crash on my computer.
It looks like it is linked to the python version. We will need more time to find a proper solution.
In the meantime, downgrading to python3.7 works for me.
You can try these commands:
sudo port install py37-matplotlib +tkinter
sudo port select --set python3 python37
then in the geoviewer folder
make clean
make -j 8
make install DESTDIR=<path to flair>
Unfortunately, the downgrading of the python version can have some issues.
In my case, I deleted all ports with the two following commands
sudo port uninstall installed
sudo port claim (answer yes to all questions)
Before performing the previous commands, I recommend you to save the list of requested ports, which would be useful to reinstall the other ports you need with the following command
port echo requested
Please let me know if this works for you.