1e4af6719c
Unlike all other nodes, the Mix node did not handle all cases of its
automatic label. This assumption was made in 02281dd26a and caused an
issue with reading uninitialized memory. In order to restrict the nodes
API interface later, this fix simply aligns the behavior of the mix node
with all others.
Pull Request: https://projects.blender.org/blender/blender/pulls/135535