use loneElement instead of onlyChecked

[mpollmeier]

No description provided.

[maltek]

didn't you just add a new message argument, to make errors from missing edges easier to understand?

[mpollmeier]

good point :)

[mpollmeier]

while writing the hints, i noticed that something like AstNode.astParentOption would be useful and I added that... would you agree?

[maltek]

while writing the hints, i noticed that something like AstNode.astParentOption would be useful and I added that... would you agree?

it is technically more correct - there are roots that just don't have a parent. IME it's rare to accidentally run into that, except with frontend bugs where crashing loudly is likely the best course of action. Usually you know where you want to go in the AST and stop long before you reach a File node. But overall it's probably good to have it there.

[mpollmeier]

ok, I guess it doesn't harm, so let's keep it there then

[mpollmeier]

The semantic change of loneElement to also error if there's more than one rather than just issuing a warning just uncovered that kotlin2cpg creates duplicate ast edges in some cases. Will create a separate ticket for that.

The error message Iterable was expected to have exactly one element, but it has 1 is obviously wrong - that's fixed in joernio/flatgraph#340

[mpollmeier]

kotlin2cpg is already fixed in #5587 - will await the merge and rebase then