As of version https://github.com/maxGraph/maxGraph/releases/tag/v0.6.0, codecs are no longer registered by default.
So stories calling directly Codecs to encode/decode may generate errors
Uncaught InternalError: too much recursion

Using ModelXmlSerializer instead will register the codecs and fix the problems.
Otherwise, call the register function if the usage of ModelXmlSerializer is not possible.