Is the double-wall.ifcx file OK?

Hi. I got an error when opening examples/Hello Wall/advanced/double-wall.ifcx

Should we open something else before loading this one?

Start by reproducing the error with examples/Hello Wall/advanced/double-wall.ifcx and inspect the surrounding Hello Wall example files for the expected loading order. Done means determining whether double-wall.ifcx is valid, whether another file must be opened first, and documenting the required correction or sequence.

Written by the indexing model from the issue text.