fix(forgejo): add caddy error message

modules/services/forgejo/default.nix

@@ -89,6 +89,11 @@ in {
     })
     (mkIf cfg.proxy {
       services.caddy.virtualHosts."${forgejoDomain}".extraConfig = ''
+        handle_errors {
+          status 502
+          respond "This server is currently unavailable."
+        }
+
         redir /user/login /user/oauth2/Keycloak?{query}
 
         reverse_proxy http://${proxyIP}:${toString cfg.port}