- ensured the configuration directives 'server' and 'username' are never empty

This patch prevents the software to keeps showing the welcome screen
  when  the main.conf  file  does not  contains at  least  one of  the
  aforementioned directive.

  The dummy server has name "invalid" and supposed to be not used in a
  DNS, see:

  https://en.wikipedia.org/wiki/.invalid

src/constants.lisp

@@ -125,9 +125,11 @@ General Public License for more details."
 (define-constant +db-file-extension+            "sqlite3"     :test #'string=
   :documentation "the extension filename of the databases")
 
-(define-constant +default-database-username+ "default" :test #'string=)
+(define-constant +default-database-username+    "default"     :test #'string=)
 
-(define-constant +default-database-server-name+ "default" :test #'string=)
+(define-constant +default-database-server-name+ "invalid"     :test #'string=)
+
+(define-constant +invalid-domain-name+          "invalid"     :test #'string=)
 
 (define-constant +json-true+                    "true"        :test #'string=)
 

src/main.lisp

@@ -201,7 +201,7 @@ etc.) happened"
     ;; same        (this       rule        is       enforced        by
     ;; 'swconf:trivial-configuration-checks')
     (when (not (or *gemini-full-screen-mode*
-                   (null (swconf::config-username))))
+                   (swconf:current-server-name-invalid-p)))
       (client:init)
       (if command-line:*fediverse-authorization-code*
           (let ((code (ui:input-dialog-immediate (_ "Authorization code"))))

src/package.lisp

@@ -59,6 +59,7 @@
    :+db-file-extension+
    :+default-database-username+
    :+default-database-server-name+
+   :+invalid-domain-name+
    :+fps+
    :+command-window-height+
    :+starting-init-file+
@@ -1510,6 +1511,8 @@
    :config-notification-icon
    :current-username
    :current-server-name
+   :current-server-name-invalid-p
+   :current-server-name-valid-p
    :all-fediverse-accounts
    :set-current-username-and-server
    :config-password-echo-character

src/software-configuration.lisp

@@ -1180,11 +1180,14 @@
                    +key-notification-icon+
                    +key-value+)
 
-(gen-simple-access (server-name)
-                   +key-server+)
 
-(gen-simple-access (username)
-                   +key-username+)
+(defun config-server-name ()
+  (or (access:accesses *software-configuration* +key-server+)
+      (list +default-database-server-name+)))
+
+(defun config-username ()
+  (or (access:accesses *software-configuration* +key-username+)
+      (list +default-database-username+)))
 
 (defun all-fediverse-accounts ()
   (loop for username in (config-username)
@@ -1200,6 +1203,13 @@
 (defun current-server-name ()
   *current-server-name*)
 
+(defun current-server-name-invalid-p ()
+  (string= (current-server-name)
+           constants:+invalid-domain-name+))
+
+(defun current-server-name-valid-p ()
+  (not (current-server-name-invalid-p)))
+
 (defun set-current-username-and-server (&optional username server-name)
   (flet ((set-currents (username server-name)
            (setf *current-username* username)