Correct. NIFs are meshes, not textures. The problem here is that the wrong file was associated with the NiSourceTexture path - you can use Nifskope to fix the error and point to the correct texture file:
Textures\LM\LM_tapestryZ.bmp
I checked the other nifs just in case, but that's the only one affected.
FYI: every one of those meshes incorrectly uses forward slashes instead of backslashes in the texture path; that will work for meshes placed loose under the '...Data Files\Meshes' folder, however such usage will cause reading of the texture path to fail if the faulty mesh is included inside a BSA archive. Changing to backslashes will work in all cases.