Creating a Nested Custom QML Component `Component` in a C++ Class - c++

Question

The Problem
I am trying to create a QML Component (and by component, I mean a QML component of type Component that gets used by a Loader's sourceComponent property) in a C++ class and pass it down to a QML File. I am using a Loader particularly to dynamically change a single area of the view based on user interaction with the UI elsewhere on that view. Here is how I am approaching the implementation:
DynamicLoader.h
class DynamicLoader: public QQuickItem {
Q_OBJECT
Q_PROPERTY(QObject *mainComp READ getMainComp NOTIFY mainCompChanged)
public:
DynamicLoader(QQuickItem *parent = Q_NULLPTR);
QObject* getMainComp() const;
private:
QObject* m_mainComp;
QObject* createComponent();
signals:
void mainCompChanged();
};
DynamicLoader.cpp
DynamicLoader::DynamicLoader(QQuickItem* parent)
: QQuickItem(parent)
, m_mainComp(new QObject(this)) {
m_mainComp = createCustomComponent();
}
QObject *DynamicLoader::getMainComp() const {
return m_mainComp;
}
QObject* DynamicLoader::createComponent() {
QQmlEngine engine;
QQmlComponent component(&engine,
QUrl::fromLocalFile("://imports/components/CustomComponent.qml"));
QObject* object = component.create();
Q_ASSERT(object);
QQuickItem* childItem = qobject_cast<QQuickItem*>(object);
childItem->setParent(this);
return childItem;
}
CustomComponent.qml
Component {
CustomTextBox {
text: "Custom Text"
}
}
CustomTextBox.qml
import QtQuick 2.0
Item {
property int containerWidth: 580
property alias text: customText.text
anchors.fill: parent
Text {
id: customText
text: "Default Text"
anchors.top: parent.top
anchors.horizontalCenter: parent.horizontalCenter
width: parent.width
verticalAlignment: Text.AlignVCenter
horizontalAlignment: Text.AlignHCenter
font.weight: Font.Bold
font.pointSize: 100
color: "white"
}
}
This, however, crashes the program with the following error message:
QQmlComponent: Component is not ready, and fails at the Q_ASSERT.
Other Findings
This same error occurs even when CustomComponent.qml is changed to simply Component {}. When I discovered this, I suspected that perhaps QQmlComponent already wraps the QML file with a Component type (please correct me if I am wrong), so I went ahead and converted the file to:
Item {
CustomTextBox {
text: "Custom Text"
}
}
and got the same error.
Only when I change the file to the following does it not error out:
Item {
Item {
}
}
Lastly, the error does not occur when I implement CustomComponent.qml entirely in QML.
Questions
Am I correct in thinking that declaring a QQmlComponent already wraps a QML file with the Component type? If not, how should I be creating a Component QML component in C++?
Why does the program crash when I create a nested custom component? Do I need to create the component through other means?
Any help and corrections to fundamental misconceptions would be greatly appreciated. Thank you.