Error Object Reference not set to an instance of an object

[Optimized_Anonymized.zip](https://github.com/youshengCode/IfcToolbox/files/11266887/Optimized_Anonymized.zip)

![image](https://user-images.githubusercontent.com/49189962/232919981-3f901762-8262-4870-a51a-7e9b47cb73ef.png)


The error shows up when trying to split the attached file.
Can somebody help with that?