r - How to skip error checking at Rmarkdown compiling?

Question

I was writing an Rmarkdown document (compile to HTML) in RStudio, and there are some code chunks that deliberately generate errors. for example:

```{r}
sum(a)
```

Since there is no previous definition for a this chunk will naturally generate an error message like object 'a' not found. I'd like this error message displayed in the final HTML file, but when I press Ctrl+Shift+K in RStudio to "Knit HTML", the compiler reported the error and stopped knitting.

So how can I tell knitr to ignore such error at compiling time and display it in the knitted HTML document?

Answer 1

Use error=TRUE: from the description of knitr chunk options,

error: (TRUE; logical) whether to preserve errors (from stop()); by default, the evaluation will not stop even in case of errors!! if we want R to stop on errors, we need to set this option to FALSE

rmarkdown::render, the function behind RStudio's "Knit HTML" button/Ctrl-Shift-K shortcut, sets error=FALSE by default (in contrast to knitr::knit, which defaults to error=TRUE)

```{r error=TRUE}
sum(a)
```