Update errorCode return type

Author: VincentLanglet

resources/functionMap.php

@@ -8678,7 +8678,7 @@
 'PDO::beginTransaction' => ['bool'],
 'PDO::commit' => ['bool'],
 'PDO::cubrid_schema' => ['array', 'schema_type'=>'int', 'table_name='=>'string', 'col_name='=>'string'],
-'PDO::errorCode' => ['string'],
+'PDO::errorCode' => ['string|null'],
 'PDO::errorInfo' => ['array'],
 'PDO::exec' => ['int|false', 'query'=>'string'],
 'PDO::getAttribute' => ['', 'attribute'=>'int'],
@@ -8721,7 +8721,7 @@
 'PDOStatement::closeCursor' => ['bool'],
 'PDOStatement::columnCount' => ['0|positive-int'],
 'PDOStatement::debugDumpParams' => ['void'],
-'PDOStatement::errorCode' => ['string'],
+'PDOStatement::errorCode' => ['string|null'],
 'PDOStatement::errorInfo' => ['array'],
 'PDOStatement::execute' => ['bool', 'bound_input_params='=>'?array'],
 'PDOStatement::fetch' => ['mixed', 'how='=>'int', 'orientation='=>'int', 'offset='=>'int'],