Cannot open three.js editor project properly

I made a simple scene in saved it and when I opened it again, only the camera angle changed at first and then only after a click, one or two children of the scene appeared in the scene view, but not also in the hierarchy. I have to refresh the page to see them in the hierarchy. The biggest problem is that not all children of the scene loaded. Does anyone know why this happens?

I’ve just noticed that I get this error in the console when I try to open my project:

three.module.js:52726 Uncaught (in promise) 
TypeError: is not a function
    at DirectionalLightHelper.update (three.module.js:52726:21)
    at new DirectionalLightHelper (three.module.js:52710:8)
    at Editor.addHelper (Editor.js:425:15)
    at Editor.js:179:10
    at DirectionalLight.traverse (three.module.js:7678:3)
    at Editor.addObject (Editor.js:173:10)
    at Editor.setScene (Editor.js:158:9)
    at Editor.fromJSON (Editor.js:679:8)
    at async onEditorCleared (Menubar.File.js:126:5)

Turns out I can’t open a project with a directional light in it (even if it is the only element added to an empty project). Is this a bug or am I missing something?