Fixed unitialized parameter in instances_path stylesheet, leading to
calls to add_instance with no data when passing datatypes insteatd of project
root. That bug was making exceptions (for exemple when editing type) when
having arrays of derivated types in project.

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<?xml version="1.0" encoding="UTF-8"?>

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<BeremizRoot URI_location="LOCAL://">

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  <TargetType/>

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</BeremizRoot>