R Error: names() applied to a non-vector
This is a tricky error. I was able to track down the reason and it seems to be that R has an object of the same name as the function cached. This is most likely if using an IDE such as RStudio a tab for View(df). Unless the tab is closed even running the function without code will give you this error. Likewise, if the tab is not closed not even removing all objects or doing a garbage collection will solve it. Once the tab is closed the error will be gone.
I had the same error, and It was faulting on a particular function that I wrote. It was throwing the error whenever I loaded the function, even when the I commented out all the code in the function. I found that changing the variable name of my function stopped the error. My only guess is that there is some weird variable name conflict.