RStudio's R Markdown template causing infinite loop: Mac OSX 'El Capitan'

[dromano]

Hi, this has never happened before, but if I use

File > New File > R Markdown...

to create the built-in template file

---
title: "Untitled"
author: "Me"
date: "4/15/2020"
output: html_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
```
## R Markdown

This is an R Markdown document. Markdown is...

and try to execute a code block, I seem to trigger an infinite loop and get this in the console:

Has anyone seen this before? I have no idea how to fix this, and it seems to happen no matter what code block I try to execute. I'm trying to have my students prepare markdown documents for their final projects, so would be very grateful for any help or insight anyone could provide.

[dromano]

HI @jonathan: I found an exchange about this on github (https://github.com/rstudio/rstudio/issues/4759#issuecomment-493155974), and was wondering if you knew of a workaround for Mac OS X El Capitan -- I don't have space to upgrade my OS, so can't use the version of RStudio that fixed the issue.