PHP 8.1 compatibility bis

Author: PowerKiKi

.github/workflows/php.yml

@@ -47,7 +47,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php: ['7.1', '7.2', '7.3', '7.4', '8.0'] #, '8.1'
+        php: ['7.1', '7.2', '7.3', '7.4', '8.0', '8.1']
     steps:
         -   name: Setup PHP
             uses: shivammathur/setup-php@v2

src/Common/XMLWriter.php

@@ -59,7 +59,7 @@ public function __construct($pTemporaryStorage = self::STORAGE_MEMORY, $pTempora
         if ($pTemporaryStorage == self::STORAGE_MEMORY) {
             $this->openMemory();
         } else {
-            if (!is_dir($pTemporaryStorageDir)) {
+            if ($pTemporaryStorageDir && !is_dir($pTemporaryStorageDir)) {
                 $pTemporaryStorageDir = sys_get_temp_dir();
             }
             // Create temporary filename
@@ -178,12 +178,12 @@ public function writeAttributeIf(bool $condition, string $attribute, $value)
      *
      * @return bool
      */
-    public function writeAttribute($name, $value)
+    public function writeAttribute($name, $value): bool
     {
         if (is_float($value)) {
             $value = json_encode($value);
         }
 
-        return parent::writeAttribute($name, $value);
+        return parent::writeAttribute($name, $value ?? '');
     }
 }