The idea is to copy/paste the output here to Discourse, select the output code with your mouse, and use below </> button to format the output so it doesnt get mangled after posting like it is now:
Could you edit your posting above to do that to clear up the mangled bits pls ?
Other than that, I see above config file present that does not come with a "standard" lite install of Raspbian/Pi-OS plus Pi-hole:
pi@ph5:~ $ apt-file search 90-javascript-alias.conf
javascript-common: /etc/lighttpd/conf-available/90-javascript-alias.conf
pi@ph5:~ $ apt policy javascript-common
javascript-common:
Installed: (none)
[..]
Whats in it ?
cat /etc/lighttpd/conf-available/90-javascript-alias.conf
Try disabling that configuration file with below:
sudo lighty-disable-mod javascript-alias
Validate its gone:
ls -1 /etc/lighttpd/conf-enabled/
Apply by running below:
sudo service lighttpd force-reload
And test the web GUI.
EDIT: if didnt fix, you can revert enabling it again by doing:
sudo lighty-enable-mod javascript-alias
sudo service lighttpd force-reload