Books: Table of Content picks up code-block comments as chapter titles

[HenrikBengtsson]

Bug description

Using

```{r, echo = FALSE}
# INITIALIZE CODE
hello <- 42
```

# Summary

In summary, this book has no content whatsoever.

in a Quarto Book chapter results in INITIALIZE CODE becoming the chapter title used in the table of content, although the Summary is still the title on the page. See below screenshot.

Session info

Ubuntu 20.04 with:

$ quarto --version
1.3.11

Checklist

• Please include a minimal, fully reproducible example in a single .qmd file? Please provide the whole file rather than the snippet you believe is causing the issue.
• Please format your issue so it is easier for us to read the bug report.
• Please document the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
• Please document the operating system you're running. If on Linux, please provide the specific distribution.

[dragonstyle]

I can confirm this (we use a line based parser to identify the title if it isn't specified in front matter, so it will be fooled by this). Placing the code chunk after the first heading is the recommended workaround for now...

[dragonstyle]

I took a closer look at this today and after some tinkering with keeping a queue that tracks code state, I feel that this change is a bit invasive / risky / sketchy to making at this point in such low level shared code.

I think the workaround to move the code cell after the H1 is a reasonable workaround for the time being.

[mcanouil]

For reference, the same issue occurring in listing:

• Listing for blog post looks for title in code cell comments #13049