From 36ed2d55d1c02ed6fe705a34fd1778300fbc5a3a Mon Sep 17 00:00:00 2001
From: Janice Collins <jcollins@google.com>
Date: Fri, 11 Jan 2019 10:46:42 -0800
Subject: [PATCH] Fix crash on invalid prefix imports.

---
 lib/src/model.dart                 | 3 ++-
 testing/test_package/lib/fake.dart | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/src/model.dart b/lib/src/model.dart
index 783adb0759..3aaa7c8d7e 100644
--- a/lib/src/model.dart
+++ b/lib/src/model.dart
@@ -2236,7 +2236,8 @@ class Library extends ModelElement with Categorization, TopLevelContainer {
       _prefixToLibrary = {};
       // It is possible to have overlapping prefixes.
       for (ImportElement i in (element as LibraryElement).imports) {
-        if (i.prefix?.name != null) {
+        // Ignore invalid imports.
+        if (i.prefix?.name != null && i.importedLibrary != null) {
           _prefixToLibrary.putIfAbsent(i.prefix?.name, () => new Set());
           _prefixToLibrary[i.prefix?.name].add(
               new ModelElement.from(i.importedLibrary, library, packageGraph));
diff --git a/testing/test_package/lib/fake.dart b/testing/test_package/lib/fake.dart
index da134b13c6..b6b147feac 100644
--- a/testing/test_package/lib/fake.dart
+++ b/testing/test_package/lib/fake.dart
@@ -48,6 +48,9 @@ library fake;
 
 import 'dart:async';
 import 'dart:collection';
+// Make sure dartdoc ignores invalid prefixes imports (#1896)
+// ignore: uri_does_not_exist
+import 'dart:json' as invalidPrefix;
 import 'package:meta/meta.dart' show Required;
 import 'csspub.dart' as css;
 import 'csspub.dart' as renamedLib2;