Page URL incorrectly states username is taken when it contains a period/invalid character #786
Description
LinkStack version
4.8.0
Description
When selecting a username on the Sign Up page, the text field for Page URL will erroneously report that a username is taken when it actually contains an invalid character (such as period/.) on the main LinkStack instance.
Details about your system
Linux/Manjaro Unstable with Brave Browser version 1.66.115-1 on the main LinkStack instance linksta.cc.
How to reproduce
Suppose multipartusername is the desired base form of the username and is not taken.
Using a pure alphanumeric multipartusername, hyphen separators like multi-part-username, or underscore separators like multi_part_username is valid.
However, multipart.username is invalid, since periods are not allowed. However, the form reports with client-side form message that says:
That username is already taken
Possible Solution
During the sign up process, if an invalid character is used for a username, then the form should tell the user that an invalid character has been used; and also the user should be told what characters are valid in usernames.
Additional Context
No response