There are some Files, fiddler needs write privileges:
rm: cannot remove '/opt/fiddler/listeningProcess.txt': Permission denied
rm: cannot remove '/opt/fiddler/gsettings.txt': Permission denied
rm: cannot remove '/opt/fiddler/proxiesFromInterfaces.txt': Permission denied
If this file is stored with the exe file, it is not possible to install fiddler in /bin or /opt and run without root privileges.
I think it would be good to locate that file in the users home folder or in /tmp.