Handle w:num with invalid w:abstractNumId

3 files changed, 20 insertions, 1 deletions

diff --git a/NEWS b/NEWS
index 937a043..2313c34 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,7 @@
+# 1.4.17
+
+* Handle w:num with invalid w:abstractNumId
+
 # 1.4.16
 
 * Convert symbols in supported fonts to corresponding Unicode characters.
diff --git a/lib/docx/numbering-xml.js b/lib/docx/numbering-xml.js
index 64c4210..832e414 100644
--- a/lib/docx/numbering-xml.js
+++ b/lib/docx/numbering-xml.js
@@ -20,7 +20,9 @@ function Numbering(nums, abstractNums, styles) {
         var num = nums[numId];
         if (num) {
             var abstractNum = abstractNums[num.abstractNumId];
-            if (abstractNum.numStyleLink == null) {
+            if (!abstractNum) {
+                return null;
+            } else if (abstractNum.numStyleLink == null) {
                 return abstractNums[num.abstractNumId].levels[level];
             } else {
                 var style = styles.findNumberingStyleById(abstractNum.numStyleLink);
diff --git a/test/docx/numbering-xml.tests.js b/test/docx/numbering-xml.tests.js
index 1eefd37..1a20ab0 100644
--- a/test/docx/numbering-xml.tests.js
+++ b/test/docx/numbering-xml.tests.js
@@ -33,6 +33,19 @@ test('w:num element inherits levels from w:abstractNum', function() {
 });
 
 
+test('w:num element referencing non-existent w:abstractNumId is ignored', function() {
+    var numbering = readNumberingXml(
+        new XmlElement("w:numbering", {}, [
+            new XmlElement("w:num", {"w:numId": "47"}, [
+                new XmlElement("w:abstractNumId", {"w:val": "42"})
+            ])
+        ]),
+        {styles: stylesReader.defaultStyles}
+    );
+    duck.assertThat(numbering.findLevel("47", "0"), duck.equalTo(null));
+});
+
+
 test('when w:abstractNum has w:numStyleLink then style is used to find w:num', function() {
     var numbering = readNumberingXml(
         new XmlElement("w:numbering", {}, [