rstudioapi randomly removes text when used in a snippet

Question

I am creating a snippet that automatically takes the name of the function defined in the line below, and creates a roxygen2 documentation where the title is printed "nicely".

I have defined the following snippet:

snippet doc
    `r
    editor <- rstudioapi::getSourceEditorContext()
    editor_start <- editor$selection[[1]]$range$start[[1]]
    start <- rstudioapi::document_position(editor_start + 1, 1)
    end <- rstudioapi::document_position(editor_start + 1, 999)
    range_ <- rstudioapi::document_range(start, end)
    
    rstudioapi::setSelectionRanges(range_, editor$id)
    text <- rstudioapi::primary_selection(
      rstudioapi::getSourceEditorContext()
    )$text
    split_text <- stringr::str_split(stringr::word(text, 1), "_", simplify = T)
    title <- stringr::str_to_title(paste(split_text, collapse =" "))
    
    start <- rstudioapi::document_position(editor_start, 1)
    end <- rstudioapi::document_position(editor_start, 999)
    range_ <- rstudioapi::document_range(start, end)
    
    rstudioapi::insertText(
        range_,
        paste("#' @title", title),
        editor[["id"]]
    )
    
    rstudioapi::setCursorPosition(c(editor_start, nchar(title) + 1))
    
    NULL`

To test, one can run the following code, and press shift + tab with cursor behind doc:

doc
test_snippet <- function(
  x, y
) {
  NULL
}

It then changes the code to the following:

#' @title Test Snippet
unction(
  x, y
) {
  NULL
}

It succesfuly writes the title in the format I expected, but it removes part of the function definition line. Any suggestions as to why this is happening, and how to solve it+