To install web-ext, run the following command in macOS terminal (Applications->Utilities->Terminal)
sudo port install web-ext
To see what files were installed by web-ext, run:
port contents web-ext
To later upgrade web-ext, run:
sudo port selfupdate && sudo port upgrade web-ext
Reporting an issue on MacPorts Trac
The MacPorts Project uses a system called Trac to file tickets to report bugs and enhancement requests.
Though anyone may search Trac for tickets, you must have a GitHub account in order to login to Trac to create tickets.