PHP 8.1 deprecated support for null values in its APIs

lib/Cli.php

@@ -456,7 +456,7 @@ protected function convert($vObj)
      */
     protected function color($vObj)
     {
-        fwrite($this->stdout, $this->serializeComponent($vObj));
+        $this->serializeComponent($vObj);
     }
 
     /**

lib/Component.php

@@ -28,7 +28,7 @@ class Component extends Node
     /**
      * A list of properties and/or sub-components.
      *
-     * @var array
+     * @var array<string, Component|Property>
      */
     protected $children = [];
 
@@ -43,12 +43,12 @@ class Component extends Node
      * an iCalendar object, this may be something like CALSCALE:GREGORIAN. To
      * ensure that this does not happen, set $defaults to false.
      *
-     * @param string $name     such as VCALENDAR, VEVENT
-     * @param bool   $defaults
+     * @param string|null $name     such as VCALENDAR, VEVENT
+     * @param bool        $defaults
      */
     public function __construct(Document $root, $name, array $children = [], $defaults = true)
     {
-        $this->name = strtoupper($name);
+        $this->name = isset($name) ? strtoupper($name) : '';
         $this->root = $root;
 
         if ($defaults) {
@@ -238,7 +238,13 @@ public function select($name)
                 return array_filter(
                     $result,
                     function ($child) use ($group) {
-                        return $child instanceof Property && strtoupper($child->group) === $group;
+                        if ($child instanceof Property) {
+                            $cgroup = isset($child->group) ? strtoupper($child->group) : '';
+
+                            return $cgroup === $group;
+                        }
+
+                        return false;
                     }
                 );
             }

lib/Parameter.php

@@ -52,11 +52,12 @@ class Parameter extends Node
      */
     public function __construct(Document $root, $name, $value = null)
     {
-        $this->name = strtoupper($name);
         $this->root = $root;
         if (is_null($name)) {
             $this->noName = true;
             $this->name = static::guessParameterNameByValue($value);
+        } else {
+            $this->name = strtoupper($name);
         }
 
         // If guessParameterNameByValue() returns an empty string

lib/Property.php

@@ -30,7 +30,7 @@ abstract class Property extends Node
      *
      * This is only used in vcards
      *
-     * @var string
+     * @var string|null
      */
     public $group;
 

lib/Property/Text.php

@@ -136,16 +136,18 @@ public function getRawMimeDirValue()
             }
 
             foreach ($item as &$subItem) {
-                $subItem = strtr(
-                    $subItem,
-                    [
-                        '\\' => '\\\\',
-                        ';' => '\;',
-                        ',' => '\,',
-                        "\n" => '\n',
-                        "\r" => '',
-                    ]
-                );
+                if (!is_null($subItem)) {
+                    $subItem = strtr(
+                        $subItem,
+                        [
+                            '\\' => '\\\\',
+                            ';' => '\;',
+                            ',' => '\,',
+                            "\n" => '\n',
+                            "\r" => '',
+                        ]
+                    );
+                }
             }
             $item = implode(',', $item);
         }

tests/phpunit.xml

@@ -10,6 +10,9 @@
   failOnWarning="true"
   enforceTimeLimit="true"
   >
+  <php>
+    <ini name="error_reporting" value="E_ALL"/>
+  </php>
   <testsuites>
     <testsuite name="Sabre\VObject">
       <directory>.</directory>