create user miss validation check

[potemkin_ai]

If I try to create user with _ in username, it silently fails, dropping the following error in the console:

(anonymous) @ angular.js:12011
n @ angular.js:11776
(anonymous) @ angular.js:11571
(anonymous) @ angular.js:16383
$eval @ angular.js:17682
$digest @ angular.js:17495
$apply @ angular.js:17790
(anonymous) @ angular.js:25890
dispatch @ jquery.min.js?32d97f9ffba9ba7a989d8ef52be913efb0d20946:3
r.handle @ jquery.min.js?32d97f9ffba9ba7a989d8ef52be913efb0d20946:3
angular.js:13920 TypeError: Cannot read properties of undefined (reading '$setPristine')
    at users.js:355:1
    at client.js:1855:1
    at client.js:282:1
    at angular.js:11486:13
    at angular.js:16383:28
    at m.$eval (angular.js:17682:16)
    at m.$digest (angular.js:17495:15)
    at m.$apply (angular.js:17790:13)
    at l (angular.js:11831:36)
    at J (angular.js:12033:7)

After POST to api/v1/users (error code 400).

Since no where in the form it says that username can't have underline, it's non-trivial to figure out what went wrong.

I guess it would be nice to have a text description in the form or, better, an input verification check, so that I couldn't make this mistake.

[nebulon]

Great catch. I have fixed up the UI now for the next release to actually show the correct error message next to the username field.

[potemkin_ai]

@nebulon Thanks!