Handle empty input to flatten_para

Fixes #656

NEWS.md

@@ -1,5 +1,8 @@
 # pkgdown 1.0.0.9000
 
+* Empty sections are now ignored (#656). Previously, empty sections caused 
+  error `Error in rep(TRUE, length(x) - 1)`.
+
 * `\tabular{}` now longer requires a terminal `\cr` (#664, #645).
 
 * Added a keyboard shortcut for searching. Press `shift` + `/` to move focus

R/rd-data.R

@@ -98,8 +98,8 @@ as_data.tag_value <- function(x, ...) {
     values <- x[-seq_len(idx - 1)]
   }
 
-  text <- if (length(text) > 0) flatten_para(text, ...) else NULL
-  values <- if (length(values) > 0) parse_descriptions(values) else NULL
+  text <- flatten_para(text, ...)
+  values <- parse_descriptions(values)
 
   list(
     title = "Value",

R/rd-html.R

@@ -5,6 +5,10 @@ as_html <- function(x, ...) {
 # Various types of text ------------------------------------------------------
 
 flatten_para <- function(x, ...) {
+  if (length(x) == 0) {
+    return(character())
+  }
+
   # Look for "\n" TEXT blocks after a TEXT block, and not at end of file
   is_nl <- purrr::map_lgl(x, is_newline, trim = TRUE)
   is_text <- purrr::map_lgl(x, inherits, "TEXT")
@@ -333,6 +337,10 @@ parse_items <- function(rd, ...) {
 }
 
 parse_descriptions <- function(rd, ...) {
+  if (length(rd) == 0) {
+    return(character())
+  }
+
   is_item <- purrr::map_lgl(rd, inherits, "tag_item")
 
   parse_item <- function(x) {

tests/testthat/test-as_html.R

@@ -181,6 +181,10 @@ test_that("code blocks autolinked to vignettes", {
 
 # Paragraphs --------------------------------------------------------------
 
+test_that("empty input gives empty output", {
+  expect_equal(flatten_para(character()), character())
+})
+
 test_that("empty lines break paragraphs", {
   expect_equal(
     flatten_para(rd_text("a\nb\n\nc")),