Offer to pass -create-admin option if no admins were found

Implements: #218

main.go

@@ -61,5 +61,9 @@ func main() {
 	// Static files:
 	static.InitFS(files.StaticFiles())
 
+	if !user.HasAnyAdmins() {
+		log.Println("Your wiki has no admin yet. Run Mycorrhiza with -create-admin <username> option to create an admin.")
+	}
+
 	serveHTTP(web.Handler())
 }

user/users.go

@@ -9,7 +9,7 @@ var tokens sync.Map
 func YieldUsers() chan *User {
 	ch := make(chan *User)
 	go func(ch chan *User) {
-		users.Range(func(_, v interface{}) bool {
+		users.Range(func(_, v any) bool {
 			ch <- v.(*User)
 			return true
 		})
@@ -38,6 +38,15 @@ func Count() (i uint64) {
 	return i
 }
 
+func HasAnyAdmins() bool {
+	for u := range YieldUsers() {
+		if u.Group == "admin" {
+			return true
+		}
+	}
+	return false
+}
+
 // HasUsername checks whether the desired user exists
 func HasUsername(username string) bool {
 	_, has := users.Load(username)