An error handler must return boolean, not void

phpcs.xml.dist

@@ -77,5 +77,6 @@
     <rule ref="SlevomatCodingStandard.TypeHints.TypeHintDeclaration.IncorrectReturnTypeHint">
         <exclude-pattern>lib/Doctrine/DBAL/Types/ArrayType.php</exclude-pattern>
         <exclude-pattern>lib/Doctrine/DBAL/Types/ObjectType.php</exclude-pattern>
+        <exclude-pattern>tests/Doctrine/Tests/DBAL/Driver/Mysqli/MysqliConnectionTest.php</exclude-pattern>
     </rule>
 </ruleset>

tests/Doctrine/Tests/DBAL/Driver/Mysqli/MysqliConnectionTest.php

@@ -44,7 +44,7 @@ class MysqliConnectionTest extends DbalFunctionalTestCase
 
     public function testRestoresErrorHandlerOnException() : void
     {
-        $handler         = static function () : void {
+        $handler         = static function () : bool {
             self::fail('Never expected this to be called');
         };
         $default_handler = set_error_handler($handler);