So for your image set it in your forum message like this:

<img src="https://i.postimg.cc/pT5wSKSF/Ohne-Titel.png">

For the error message, have you possibly removed the scene browser with some of your changes?

If so then you'll need to modify DeathPane.js and remove the piece of it where it is trying to access the scene browser and expand the sections during program startup.

That would be the part that goes like this:

var items = moi.ui.sceneBrowser.rootItems;
for ( var i = 0; i < items.length; ++i )
    items[i].expanded = true;

- Michael