Inconsistent webserver check in installer/updater (installer_base.lib.php)

There is an issue (but it is not a big deal) with the installer/updater when both webservers are installed on the same system.
This can happen quite often on EL systems where, due to package dependencies, both webservers are installed but only one is used.

I dunno about Debian/Ubuntu, but for EL systems the following PHP warnings appears:

Configuring Postfix
Configuring Dovecot
Configuring Spamassassin
Configuring Rspamd
Configuring Getmail
Configuring Pureftpd
Configuring Apache
Configuring vlogger
Configuring Apps vhost
PHP Warning: symlink(): No such file or directory in /var/share/dev/ispconfig/install/lib/installer_base.lib.php on line 2905
Configuring Jailkit
Configuring Database
Updating ISPConfig
PHP Warning: symlink(): No such file or directory in /var/share/dev/ispconfig/install/lib/installer_base.lib.php on line 2985
ISPConfig Port [8080]:

Create new ISPConfig SSL certificate (yes,no) [no]:

Reconfigure Crontab? (yes,no) [yes]:

Maybe this can be addressed together with the Apache/Nginx Reverse Proxy issue #6479 because these warnings do not cause any actual problems.