can't roxygenise file if string contains code that doesn't parse

[mcol]

Copy the following into a file:

#' Example
#'
#' Shows some buggy behaviour.
#'
#' ```
#' msg <- "Error in if (ncol(dat$y)) {: argument is of length zero"
#' ```
#' @name test
NULL

The following error is produced:

roxygen2::roxygenise()

# ℹ Loading test
# ✖ test.R:5: @details has mismatched braces or quotes.
# Writing test.Rd

The expectation is that there should be no error. This is a minimal example of a bug reported in r-lib/cli#803.