styler malforms text in Visual Markdown mode

[jthomasmock]

Hi @kevinushey I originally opened the issue in {styler}, and have moved it to here at Lorenz' request.

r-lib/styler#740 (comment)

I have copied the bulk of that post below. I can reproduce interactively, and have included a GIF of the behavior.

---

System details

RStudio Edition :  Desktop
RStudio Version : 1.4.1103
OS Version      : x86_64-apple-darwin17.0 (64-bit), macOS Catalina 10.15.7
R Version       : 4.1

Steps to reproduce the problem

Problem: In Visual Markdown mode, styling the active selection in a code-chunk appears to correctly style the code, but malforms it on the plain-text side.

Switching back into plain-text mode, the code will be "fixed", but if you "undo" you can see there is an intermediate format that is completely malformed and has lost some characters. Undo a second time will revert back to the original, unstyled format.

Reprex below, and note this works fine in non-visual editor mode.

---
output: html_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
library(tidyverse)
```



Use the `styler` package to "style" the code.
Code intentionally awkwardly formatted and of sufficient length as an example.

```{r}
mpg %>%     filter(cyl   %in%c(4 , 6,     8))%>%slice_sample(n=30) %>% mutate(hwy_mpl = hwy/2.352)
```

Environment:

## Packages of interest
styler V: 1.3.2
rstudioapi V: 0.13

Quick recording

Describe the problem in detail

Problem: In Visual Markdown mode, styling the active selection in a code-chunk appears to correctly style the code, but malforms it on the plain-text side temporarily which persists unless swapping back and forth between plain text and visual mode.

Describe the behavior you expected

Expected that styling the code would organize the code according to the style guide, and that the code would be able to run even in Visual Markdown mode.

• I have read the guide for submitting good bug reports.
• I have installed the latest version of RStudio, and confirmed that the issue still persists.
• If I am reporting a RStudio crash, I have included a diagnostics report.
• I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.