Steps to replicate the issue (include links if applicable):
What happens?:
User doesn't have passkeys and using a browser that does not support passkeys, is unable to login and receives the error:
This browser does not support security key authentication, or it is not available for this website. Please try with a different browser.
The condition they hit seems to be !window.PublicKeyCredential which immediately throws an error.
What should have happened instead?:
Users with browsers not supported passykeys should continue to be able to use normal login
Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):
Other information (browser name/version, screenshots, etc.):