From 1dba641d6740ca05889de8a8cbe4753f73cbad6c Mon Sep 17 00:00:00 2001
From: Titus Wormer <tituswormer@gmail.com>
Date: Tue, 9 Feb 2021 11:43:55 +0100
Subject: [PATCH] Fix exception on tree w/o `children`

---
 index.js |  3 ++-
 test.js  | 16 ++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/index.js b/index.js
index 0055646..6ff76ed 100644
--- a/index.js
+++ b/index.js
@@ -215,7 +215,8 @@ function messageControl(options) {
 
 // Detect gaps in `tree`.
 function detectGaps(tree, file) {
-  var lastNode = tree.children[tree.children.length - 1]
+  var children = tree.children || []
+  var lastNode = children[children.length - 1]
   var offset = 0
   var gaps = []
   var gap
diff --git a/test.js b/test.js
index ecef908..aa07dc2 100644
--- a/test.js
+++ b/test.js
@@ -727,5 +727,21 @@ test('control()', function (t) {
       )
     })
 
+  remark()
+    .use(function () {
+      return function (tree, file) {
+        file.message('Error')
+        delete tree.children
+        control({name: 'foo', marker: mdastMarker})(tree, file)
+      }
+    })
+    .process('', function (error, file) {
+      t.deepEqual(
+        [error].concat(file.messages.map(String)),
+        [null, '1:1: Error'],
+        'should not fail when there are messages but no `children` on `tree`'
+      )
+    })
+
   t.end()
 })