Calling PdfReader.Open -> InvalidOperationException: Cannot retrieve stream length.

[sebastianhille]

For a specific set of documents I get the error "InvalidOperationException: Cannot retrieve stream length." that is thrown in the method "private int GetStreamLength(PdfDictionary dict)" from the class "PdfSharpCore/Pdf.IO/Parser.cs". In the github code for that method I also see the comment "// HACK: Solve problem more general.", so I assume that there could be an issue and I so happen to encounter this issue.
Anyone else got this problem with specific pdf documents? Is there a workaround?
Sadly I can't provide the documents where we encounter the error.