Unable to change color theme using C++

The only interface I found for setting the view theme in a C++ plugin is the ConfigInterface, but it doesn't seem to work.

The implementation I found is here } else if (key == QLatin1String("theme") && value.type() == QVariant::String) {, but this line is never reached because this prior condition if (value.canConvert<QColor>()) { is always true and the function exits before reaching the other line.

Test code used:

void setTheme(const QString &theme)
{
    auto* app = KTextEditor::Editor::instance()->application();
    for (auto* win : app->mainWindows()) {
        for (auto* view : win->views()) {
            auto* viewcfg = qobject_cast<KTextEditor::ConfigInterface*>(view);
            if (viewcfg) {
              viewcfg->setConfigValue("theme", theme);
            }
        }
    }
}

Test for QVariant::canConvert:

#include <QVariant>
int main() {
  QVariant v = "abcd";
  printf("%d\n", v.canConvert(QVariant::Color)); // 1
}