Steps to reproduce the issue

• Install J4 at launch.joomla.org
• open User-Account
• Tabs are below each other; "W3C Web Authentication (WebAuthn) Login" show Error:
  

Expected result

no Error

Actual result

see "Steps to reproduce the issue"

System information (as much as possible)

php: Linux lamp120.cloudaccess.net 3.10.0-962.3.2.lve1.5.24.7.el6h.x86_64 #1 SMP Mon Dec 17 12:02:35 EST 2018 x86_64
dbserver: mysql
dbversion: 5.7.30-cll-lve
dbcollation: utf8_general_ci
dbconnectioncollation: utf8mb4_general_ci
dbconnectionencryption:
dbconnencryptsupported: true
phpversion: 7.3.19
server: Apache
sapi_name: cgi-fcgi
version: Joomla! 4.0.0-beta4-dev Development [ Mañana ] 29-July-2020 18:21 GMT
useragent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:80.0) Gecko/20100101 Firefox/80.0

Additional comments

CredentialsCreation.php line 92:

Site Name is by default empty. Enter a Site name or deactivate Plugin "System - WebAuthn Passwordless Login" the Error is gone.