Error trying to export in Inkscape 1.3 with Python 3.11.4

Hi,

I was trying to create 236 labels using this plugin. When I click on "Apply", it shows this error:

Traceback (most recent call last): File "C:\Users\Carlos\AppData\Roaming\inkscape\extensions\next_gen.py", line 198, in <module> NextGenerator().run() File "C:\Programas\Inkscape\share\inkscape\extensions\inkex\base.py", line 250, in run self.save_raw(self.effect()) File "C:\Users\Carlos\AppData\Roaming\inkscape\extensions\next_gen.py", line 80, in effect search_string = "%VAR_" + key + "%" TypeError: can only concatenate str (not "NoneType") to str

I'm using Inkscape 1.3 and Python 3.11.4. on a Windows 10. Thanks.