fix: Regression on PHP 8.x for connection check

lib/Horde/Imap/Client/Base.php

@@ -748,8 +748,8 @@ public function getNamespaces(
          * "Array to string conversion" on PHP 8+. */
         $normalized = [];
         foreach ($additional as $val) {
-            if (is_array($val) ||
-                (is_object($val) && !($val instanceof Stringable))) {
+            if (is_array($val)
+                || (is_object($val) && !($val instanceof Stringable))) {
                 continue;
             }
             $normalized[] = strval($val);
@@ -902,7 +902,12 @@ abstract protected function _login();
      */
     public function logout()
     {
-        if ($this->_isAuthenticated && $this->_connection->connected) {
+        // shutdown() reaches this via register_shutdown_function; if the
+        // client was torn down before _connection was materialized we
+        // still want to zero the state below, so guard the connection
+        // read explicitly rather than relying on _isAuthenticated as a
+        // proxy - PHP 8+ warns on ->connected of null.
+        if ($this->_isAuthenticated && $this->_connection !== null && $this->_connection->connected) {
             $this->_logout();
             $this->_connection->close();
         }

test/Unit/Base/BaseLogoutNullConnectionTest.php

@@ -0,0 +1,70 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Copyright 2026 Horde LLC (http://www.horde.org/)
+ *
+ * See the enclosed file LICENSE for license information (LGPL). If you
+ * did not receive this file, see http://www.horde.org/licenses/lgpl21.
+ *
+ * @copyright  2026 Horde LLC
+ * @license    http://www.horde.org/licenses/lgpl21 LGPL 2.1
+ */
+
+namespace Horde\Imap\Client\Test\Unit\Base;
+
+use Horde\Imap\Client\Test\Stub\Base;
+use PHPUnit\Framework\Attributes\CoversNothing;
+use PHPUnit\Framework\TestCase;
+use ReflectionClass;
+
+/**
+ * Regression test for logout() null-connection guard.
+ *
+ * Historically Horde_Imap_Client_Base::logout() read
+ * `$this->_connection->connected` when `_isAuthenticated` was true.
+ * If an authenticated client was torn down before _connection was
+ * materialized (or after it had been cleared and _isAuthenticated
+ * still flagged true), PHP 8+ raised
+ * "Attempt to read property 'connected' on null" from shutdown().
+ * PHPUnit's `failOnWarning="true"` in phpunit.xml.dist turns the
+ * warning into a test failure — the assertion is implicit.
+ */
+#[CoversNothing]
+class BaseLogoutNullConnectionTest extends TestCase
+{
+    /**
+     * When _isAuthenticated is true but _connection is null,
+     * logout() must not warn on the ->connected read; it should
+     * zero the state and return cleanly.
+     */
+    public function testLogoutWithAuthenticatedFlagAndNullConnectionDoesNotWarn(): void
+    {
+        $ob = new Base([
+            'username' => 'user',
+            'password' => 'pass',
+        ]);
+
+        // Force the exact state the CI stack trace observed:
+        // _isAuthenticated = true, _connection = null. Reflection
+        // is needed because both properties are protected and no
+        // setter exists (nor should one — this state is only
+        // reachable through internal lifecycle races).
+        $reflection = new ReflectionClass($ob);
+
+        $authProperty = $reflection->getProperty('_isAuthenticated');
+        $authProperty->setValue($ob, true);
+
+        $connProperty = $reflection->getProperty('_connection');
+        $connProperty->setValue($ob, null);
+
+        // logout() is where the warning fired. If it warns here, the
+        // test fails via phpunit.xml.dist's failOnWarning="true".
+        $ob->logout();
+
+        // State should be zeroed regardless of the pre-call condition.
+        $this->assertFalse($authProperty->getValue($ob));
+        $this->assertNull($connProperty->getValue($ob));
+    }
+}