config parameter fail_on_error does not default to false in pull request previews

[zkamvar]

In https://github.com/carpentries-incubator/r-tidyverse-4-datasets/runs/7198272825?check_suite_focus=true#step:8:29, the build indicates that fail_on_error: true, but the config.yaml file does not contain the fail_on_error key.

The problem (I believe) is the fact that the variable I'm defining as error is representative of fail_on_error and not error in the R Markdown sense (where error = TRUE means that errors do not cause failures), which makes the code pretty confusing to read:

sandpaper/R/build_markdown.R

Lines 98 to 111 in e26d5f9

	error <- this_metadata$get()[["fail_on_error"]]
	error <- !is.null(error) && !error
	if (!error && !quiet) {
	cli::cli_alert_info("{.code fail_on_error: true}. Use {.code error=TRUE} in code chunks for demonstrative errors")
	}
	for (i in seq_along(build_me)) {
	build_episode_md(
	path = build_me[i],
	outdir = outdir,
	workdir = outdir,
	quiet = quiet,
	error = error
	)