Are you saying i should print a warning?
I wasnt sure about it, it could happen often

I'm not happy about the warnings either :D Because their are a hint but are often times ignored anyway if its not clear why they are shown or as long as there is no supervisor who complains about them.

We have a similar situation in the ViewTypeHierarchy - there we have to check if the TH contains the vertex/ClassType - and sometimes we already know they do exist because we got the vertex from the TypeHierarchy and in those cases we don't need the additional check. And if its not there we throw an exception so the caller can differentiate between: vertex is unknown and vertex has none of the desired properties the method should calculate (i.e. Collections.empty() would be returned in both cases otherwise). Please check if the analogy is applicable/reasonable in this use case.

TLDR: is it avoidable to run into theses situations (where a log would (then) be printed)?

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