Linking a datablock from a library does not update the namemap, but
there is an assert added in 47672bd06a that checks this at the end
of library linking.
Usually it does not trigger because the namemap does not exist, and it
is cleared at the end of the process. Now clear it earlier, at the
moment the namemap becomes invalid.
Pull Request: https://projects.blender.org/blender/blender/pulls/122182