Hashpipe-style chunk options cause learnr to crash

[jimjam-slam]

System details

Output of sessioninfo::session_info()():

R version 4.2.3 (2023-03-15)
Platform: aarch64-unknown-linux-gnu (64-bit)
Running under: Ubuntu 22.04.2 LTS

Matrix products: default
BLAS:   /usr/lib/aarch64-linux-gnu/openblas-pthread/libblas.so.3
LAPACK: /usr/lib/aarch64-linux-gnu/openblas-pthread/libopenblasp-r0.3.20.so

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
 [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods  
[7] base     

other attached packages:
[1] learnr_0.11.4.9000 shiny_1.7.4       

loaded via a namespace (and not attached):
 [1] Rcpp_1.0.10       compiler_4.2.3    bslib_0.4.2      
 [4] later_1.3.0       jquerylib_0.1.4   tools_4.2.3      
 [7] digest_0.6.31     memoise_2.0.1     jsonlite_1.8.4   
[10] evaluate_0.20     lifecycle_1.0.3   checkmate_2.2.0  
[13] rlang_1.1.0       cli_3.6.0         rstudioapi_0.14  
[16] parallel_4.2.3    yaml_2.3.7        xfun_0.40        
[19] fastmap_1.1.1     withr_2.5.0       stringr_1.5.0    
[22] knitr_1.42        rappdirs_0.3.3    htmlwidgets_1.6.1
[25] sass_0.4.5        vctrs_0.6.3       systemfonts_1.0.4
[28] rprojroot_2.0.3   glue_1.6.2        R6_2.5.1         
[31] rmarkdown_2.20    magrittr_2.0.3    backports_1.4.1  
[34] promises_1.2.0.1  ellipsis_0.3.2    htmltools_0.5.4  
[37] mime_0.12         xtable_1.8-4      httpuv_1.6.9     
[40] renv_1.0.2.9000   stringi_1.7.12    cachem_1.0.7     
[43] crayon_1.5.2 

Example application or steps to reproduce the problem

Works:

---
title: "Hello, Tutorial!"
output: learnr::tutorial
runtime: shiny_prerendered
---

```{r setup, include=FALSE}
library(learnr)
```

This code computes the answer to one plus one,
change it so it computes two plus two:

```{r addition, exercise=TRUE}
1 + 1
```

Does not work:

---
title: "Hello, Tutorial!"
output: learnr::tutorial
runtime: shiny_prerendered
---

```{r}
#| label: setup
#| include: FALSE
library(learnr)
```

This code computes the answer to one plus one,
change it so it computes two plus two:

```{r}
#| label: addition
#| exercise: TRUE
1 + 1
```

Also does not work:

---
title: "Hello, Tutorial!"
output: learnr::tutorial
runtime: shiny_prerendered
---

```{r}
#| setup, include=FALSE
library(learnr)
```

This code computes the answer to one plus one,
change it so it computes two plus two:

```{r}
#| addition, exercise=TRUE
1 + 1
```

Describe the problem in detail

I generally use Quarto these days, and I'm afraid I've gotten a little too used to the hashpipe-style YAML chunk options it offers! 😅

When trying out the simple {learnr} demo, I noticed that it works great as is, but if I try to modify it to use hashpipe-style chunk options (using either the YAML syntax or the comma-separated one, {learnr} crashes as soon as a user-runnable code chunk is executed (which, depending on how the document is structured, is either on first run or when a code window's Run button is pushed).

[gadenbuie]

Thanks for the report @jimjam-slam! There's something unusual happening with knitr when #| label: addition is used instead of {r addition}. learnr's code could be more defensive against these differences (I'll have a PR up shortly) but I think it's also an inconsistency worth fixing in knitr (I'll file a bug report shortly as well).

For now, I'd recommend declaring the chunk label in the chunk header. This is working for me:

---
title: "Hello, Tutorial!"
output: learnr::tutorial
runtime: shiny_prerendered
---

```{r}
#| label: setup
#| include: FALSE
library(learnr)
```

This code computes the answer to one plus one,
change it so it computes two plus two:

```{r}
#| label: addition
#| exercise: TRUE
1 + 1
```

As is this pattern:

```{r addition}
#| exercise=TRUE
1 + 1
```