If you receive this error when attempting to use a zero-length variable name, it is likely that you have a missing backtick. This is because this character is considered disallowed in the global environment. However, this problem does not affect the read CSV or parser functions. Therefore, it is important to make sure that the name of your variable does not contain the character.
To get rid of this error, you should omit any backtick characters from your rmarkdown code. However, this will not eliminate the problem entirely. Therefore, you should check your code for backticks before trying to run it. If you still get the error, you should try to avoid using rmarkdown.
A quick way to fix this problem is to simply delete the line of r code that has backtick characters. This will prevent the error from happening. This will produce a long result that will look weird. Fortunately, this is a very uncommon error. You can also try to avoid the save option when quitting a session in Rstudio.
Using two different formats can be risky. If you mix R code and markdown code, RStudio will automatically attempt to run the code as markdown, which isn’t safe. You can manually run separate chunks of code by clicking on the green play button.