#3515 use alert instead 500 for duplicated login source name

models/user.go

@@ -46,7 +46,6 @@ var (
 	ErrEmailNotExist         = errors.New("E-mail does not exist")
 	ErrEmailNotActivated     = errors.New("E-mail address has not been activated")
 	ErrUserNameIllegal       = errors.New("User name contains illegal characters")
-	ErrLoginSourceNotExist   = errors.New("Login source does not exist")
 	ErrLoginSourceNotActived = errors.New("Login source is not actived")
 	ErrUnsupportedLoginType  = errors.New("Login source is unknown")
 )