Some comments added, and Deviance class tested, with the conclusion that there is possibly a bug in the *R implementation from lme4pureR* (https://github.com/lme4/lme4pureR/issues/9). But my implementation looks fine.
Some comments added, and Deviance class tested, with the conclusion that there is possibly a bug in the *R implementation from lme4pureR* (https://github.com/lme4/lme4pureR/issues/9). But my implementation looks fine.

agisga/mixed_models,pjotrp/mixed_models,pjotrp/mixed_models,pjotrp/mixed_models,agisga/mixed_models