(The files does not seem to be corrupt since I can still load it with above code on another Mac that I have not updated the OS on yet. I've alos tried saving without any compression and rda-format )
Im using R version 3.6.2 (2019-12-12); and RStudio Version 1.2.5033.
The connection problem isn't limited to Catalina; it also occurs on Ubuntu 19.10. As you noted, the rds file is fine, which I confirmed by downloading and opening it with read, readRDS and readr::read_rds and to see, among others " model is based on the words and valence ratings".
I did notice that the parent directory is HTTP 413, which may or may not be relevant.