fix #2587: convert_ipynb() no longer drops raw cells with no format in metadata

Author: yihui

NEWS.md

@@ -7,6 +7,8 @@ rmarkdown 2.30
 
 - Dropped the temporary workaround that used to support syntax highlighting of `|>` and `=>`. The workaround has no longer been necessary since [Pandoc 2.18](https://github.com/jgm/pandoc/releases/tag/2.18), which was released more than 3 years ago (#2290).
 
+- `convert_ipynb()` no longer drops raw cells with no `format` in metadata (thanks, @katrinabrock, #2587).
+
 
 rmarkdown 2.29
 ================================================================================

R/jupyter.R

@@ -104,9 +104,9 @@ r_line_magics <- paste0('^%?(', paste(line_magics, collapse = '|'), ')($|\\s)')
 
 # convert raw text/html and text/latex cells to raw ```{=format}` Markdown blocks
 cell_raw <- function(x, fmt) {
-  if (length(fmt) != 1) return()
+  if (length(fmt) != 1) return(x)
   fmt <- switch(fmt, 'text/html' = 'html', 'text/latex' = 'latex')
-  if (length(fmt) == 0) return()
+  if (length(fmt) == 0) return(x)
   c(sprintf('```{=%s}', fmt), x, '```')
 }