Error: System.NullReferenceException: Object reference not set to an instance of an object. at DocxMerge.Program.Main(String[] args)

[vharihar2]

When I run DocxMerge as follows, I get the following error. Pls help.

DocxMerge.exe -v -i <file1.docx> <file2.docx> -o "merged.docx" -f

Creating initial document
Opening merged.docx for writing
Adding <file2.docx> to merged.docx
System.NullReferenceException: Object reference not set to an instance of an object.
at DocxMerge.Program.Main(String[] args)