Undefined nodes on Items.xml create ghost custumes (fucks costume xmldata)

You are reading that correctly, theres a vanilla oddity that makes it so undefined nodes on items.xml create null costumes...which, ofc, are not accounted for in xmldata and offset everything potentially fucking some related repentogon functionality.
Granted, yes, we can wash our hands on this one to a degree because "that xml is not valid" but its so easy to fuck that we may need to look into it eventually. Also its worth investigating what other silly effects undefined nodes cause in other xmls.
As an example, in case I'm not being clear with whats an undefined node:

<items root="yadayada">
       <stinko name="garbage" />
</items>

On this case, the stinko node will create an empty null costume...for some reason.

Start by reproducing the undefined-node example in Items.xml and tracing how it becomes a null costume in the XML data handling. Identify whether other XML inputs show similar effects; done means the behavior is understood and the resulting costume or related functionality is handled consistently.