QT Creator下运行cpp文件出现不能将参数1从"nullptr"转换为"const QSharedPointer

[Tonypaker23]

QT Creator下,运行cpp文件出现不能将参数1从"nullptr"转换为"const QSharedPointer,,
代码如下
QSharedPointer<Message> MessageFactory::create(const QString &sender, const QByteArray &data,
int type) const {
switch (type) {
case Message::TextMessage:
// As with std::shared_ptr, a QSharedPointer to a base class can hold a derived class pointer.
return QSharedPointer<Message>(new TextMessage(sender, QString::fromUtf8(data)));
// TODO: handle other message types
}
return nullptr;
}
最后在return nullptr中出错。不能将参数1从"nullptr"转换为"const QSharedPointer,,