Improve error messaging when server is not reachable

radicale/web/internal_data/js/api/common.js

@@ -0,0 +1,33 @@
+/**
+ * This file is part of Radicale Server - Calendar Server
+ * Copyright © 2017-2024 Unrud <unrud@outlook.com>
+ * Copyright © 2023-2024 Matthew Hana <matthew.hana@gmail.com>
+ * Copyright © 2024-2025 Peter Bieringer <pb@bieringer.de>
+ * Copyright © 2026-2026 Max Berger <max@berger.name>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * @param {XMLHttpRequest} request
+ * @returns {string}
+ */
+export function to_error_message(request) {
+    let have_status_text = (request.statusText != null && request.statusText != undefined && request.statusText != '')
+    if ((request.status == 0) && (!have_status_text)) {
+        return "Could not connect to server";
+    }
+
+    return request.status + " " + request.statusText;
+}