diff --git a/system/Common.php b/system/Common.php
index 257c238d2b42..30e28a1dc840 100644
--- a/system/Common.php
+++ b/system/Common.php
@@ -1013,10 +1013,26 @@ function single_service(string $name, ...$params)
      */
     function slash_item(string $item): ?string
     {
-        $config     = config(App::class);
+        $config = config(App::class);
+
+        if (! property_exists($config, $item)) {
+            return null;
+        }
+
         $configItem = $config->{$item};
 
-        if (! isset($configItem) || empty(trim($configItem))) {
+        if (! is_scalar($configItem)) {
+            throw new RuntimeException(sprintf(
+                'Cannot convert "%s::$%s" of type "%s" to type "string".',
+                App::class,
+                $item,
+                gettype($configItem)
+            ));
+        }
+
+        $configItem = trim((string) $configItem);
+
+        if ($configItem === '') {
             return $configItem;
         }
 
diff --git a/tests/system/CommonFunctionsTest.php b/tests/system/CommonFunctionsTest.php
index 9410b13322c1..4f27a8ab2f2c 100644
--- a/tests/system/CommonFunctionsTest.php
+++ b/tests/system/CommonFunctionsTest.php
@@ -30,6 +30,7 @@
 use Config\Modules;
 use Config\Services;
 use Kint;
+use RuntimeException;
 use stdClass;
 use Tests\Support\Models\JobModel;
 
@@ -392,9 +393,28 @@ public function testReallyWritable()
 
     public function testSlashItem()
     {
-        $this->assertSame('/', slash_item('cookiePath')); // slash already there
-        $this->assertSame('', slash_item('cookieDomain')); // empty, so untouched
-        $this->assertSame('en/', slash_item('defaultLocale')); // slash appended
+        $this->assertSame('/', slash_item('cookiePath')); // /
+        $this->assertSame('', slash_item('cookieDomain')); // ''
+        $this->assertSame('en/', slash_item('defaultLocale')); // en
+        $this->assertSame('7200/', slash_item('sessionExpiration')); // int 7200
+        $this->assertSame('', slash_item('negotiateLocale')); // false
+        $this->assertSame('1/', slash_item('cookieHTTPOnly')); // true
+    }
+
+    public function testSlashItemOnInexistentItem()
+    {
+        $this->assertNull(slash_item('foo'));
+        $this->assertNull(slash_item('bar'));
+        $this->assertNull(slash_item('cookieDomains'));
+        $this->assertNull(slash_item('indices'));
+    }
+
+    public function testSlashItemThrowsErrorOnNonStringableItem()
+    {
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessage('Cannot convert "Config\\App::$supportedLocales" of type "array" to type "string".');
+
+        slash_item('supportedLocales');
     }
 
     protected function injectSessionMock()