Username cannot contain . # $ [ ]

[tom10271]

Error message:
[Error] Error: Firebase.child failed: First argument was an invalid path: "A.B". Paths must be non-empty strings and can't contain 
    validatePathString (firebase-debug.js, line 8674)
    child (firebase-debug.js, line 12819)
    _setupDataEvents (firechat.js, line 120)
    (anonymous function) (firechat.js, line 263)

If user's username contain any characters that cannot be in Firebase's path, it will trigger this error message making user cannot logon to Firechat app

[jwngr]

We would need to do some work to add support for usernames with characters which are not allowed as part of Firebase key names. Until that happens, you will need to ensure usernames escape these characters.