HTMLDocument.registerElement is deprecated.

[VitaliyPlita]

Use customElements.define instead of document.registerElement see https://javascript.info/custom-elements

HTMLDocument.registerElement (file:///C:/Users/Vitaliy.Plita/AppData/Local/atom/app-1.63.1/resources/app.asar/static/index.js:160:12)
registerElement (C:\Users\Vitaliy.Plita\.atom\packages\plantuml-viewer\node_modules\space-pen\lib\space-pen.js:66:88)
Builder.openTag (C:\Users\Vitaliy.Plita\.atom\packages\plantuml-viewer\node_modules\space-pen\lib\space-pen.js:297:27)
Builder.tag (C:\Users\Vitaliy.Plita\.atom\packages\plantuml-viewer\node_modules\space-pen\lib\space-pen.js:274:12)
Function.div (C:\Users\Vitaliy.Plita\.atom\packages\plantuml-viewer\node_modules\space-pen\lib\space-pen.js:83:49)
Function.content (C:\Users\Vitaliy.Plita\.atom\packages\plantuml-viewer\lib\plantuml-viewer-view.js:16:22)

[MCF241]

I have same issue with new fork Pulsar" editor.