RGB KeyError

[AstroWildcat]

Whenever I click on the "Generate Material List" button, I get the following error:

Python: Traceback (most recent call last):
File "C:\Users\Wildcat\AppData\Roaming\Blender Foundation\Blender\2.92\scripts\addons\material-combiner-addon-master\operators\ui\combine_list.py", line 26, in execute
mat_dict = sort_materials(get_materials(ob))
File "C:\Users\Wildcat\AppData\Roaming\Blender Foundation\Blender\2.92\scripts\addons\material-combiner-addon-master\utils\materials.py", line 65, in sort_materials
mat_dict[(path, get_diffuse(mat) if mat.smc_diffuse else None)].append(mat)
File "C:\Users\Wildcat\AppData\Roaming\Blender Foundation\Blender\2.92\scripts\addons\material-combiner-addon-master\utils\materials.py", line 88, in get_diffuse
return rgb_to_255_scale(mat.node_tree.nodes['RGB'].outputs[0].default_value[:])
KeyError: 'bpy_prop_collection[key]: key "RGB" not found'

location: :-1

Is there anything that can be done about this?