An error message keeps showing with the sp-theme component:

UDT:

./main.js:1109 Uncaught TypeError: Cannot read properties of undefined (reading 'warn')
at r7.attributeChangedCallback (VM11 main.js:1109)
at uxp://uxp-internal/domjsscripts.js:2
at y.attributeChangedCallback (uxp://uxp-internal/domjsscripts.js:2)
at Object.didChangeAttributeForCustomElement (uxp://uxp-internal/domjsscripts.js:2)
at l.didChangeAttributeForElement (uxp://uxp-internal/domjsscripts.js:2)
at e.exports.didChangeAttributeForElement (uxp://uxp-internal/domjsscripts.js:2)
at didChangeAttribute (uxp://uxp-internal/domjsscripts.js:2)
at set value [as value] (uxp://uxp-internal/domjsscripts.js:2)
at set nodeValue [as nodeValue] (uxp://uxp-internal/domjs_scripts.js:2)
at r7.setAttribute (uxp://uxp-internal/domjsscripts.js:2)

main.js

require("@spectrum-web-components/theme/sp-theme.js");
require("@spectrum-web-components/theme/src/themes.js");
require("@spectrum-web-components/theme/src/express/themes.js");

index.html

<sp-theme id="panel-theme" system="spectrum" color="light" scale="medium" dir="ltr">
<header id="panel-header">
<sp-switch id="language-switch" dir="ltr" size="m" focusable="" data-js-focus-visible="">DE/EN</sp-switch>
</header>
<main id="panel-main">
...