SimpleXMLElement::addChild(): Argument #1 ($qualifiedName) must be of type string, int given

Xml::toXml 39行 self::toXml($value, $xml->addChild($key)); 当传入的数据为列表时，该处没有处理key为数字的情况，如：参数为
[
'item' => [
[
'itemCode' => '5110093',
'itemId' => '10415'
],
[
'itemCode' => '5110092',
'itemId' => '10412'
],
]

]

Start at Xml::toXml around line 39 and reproduce the failure with the nested list shown in the issue. Inspect how numeric keys reach SimpleXMLElement::addChild(); done means the example data can be converted to XML without the qualifiedName type error.

Written by the indexing model from the issue text.