Error in file-selected QML file reported as coming from base file

In my case I had a Theme.qml file and a +material/Theme.qml file, and the latter was being loaded by the error was reported for the former:

pragma Singleton

import QtQml
import QtQuick.Controls.Material

QtObject {
    property color focusColour: Material.accent
}

qrc:/qml/ui/Theme.qml:26:5: color is not a type