Explicitly include NULL as a value that tagQueryFindDescendants_() shouldn't traverse (#408)

Author: cpsievert

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: htmltools
 Type: Package
 Title: Tools for HTML
-Version: 0.5.6
+Version: 0.5.7
 Authors@R: c(
   person("Joe", "Cheng", role = "aut", email = "[email protected]"),
   person("Carson", "Sievert", role = c("aut", "cre"), email = "[email protected]", comment = c(ORCID = "0000-0002-4958-2844")),

NEWS.md

@@ -1,3 +1,9 @@
+# htmltools 0.5.7
+
+## Improvements
+
+* `tagQuery()` no longer throws an error when attempting to traverse a NULL value with r-devel. (#407)
+
 # htmltools 0.5.6
 
 ## Possibly breaking changes

R/tag_query.R

@@ -1532,7 +1532,7 @@ tagQueryFindDescendants_ <- function(el, selector, fn) {
   } else if (is.list(el)) {
     # For each item in the list like object, recurse through
     walk(el, tagQueryFindDescendants_, fn = fn, selector = selector)
-  } else if (is.atomic(el) || is.function(el) || is.language(el)) {
+  } else if (is.null(el) || is.atomic(el) || is.function(el) || is.language(el)) {
     # Can not match on atomics or functions
     return()
   } else {