This has reappeared for me again. If I have a project and I add a sampler to it and load a sample map, when I go to save the xml I get this error and I can't save a .hip at all. It just says in the console that it's saved to the project's Presets folder, but nothing is in there.
This doesn't happen with a new project, but once the project is closed and reopened it happens.
Edit: Ahhhh if I remove the setAllowDuplicateSamples line then I don't get this either... everything's connected :( https://forum.hise.audio/topic/10719/allowduplicatesamples-causing-crash