Failsafe for unavailable project info (sdk#24947).

See: https://github.com/dart-lang/sdk/issues/24947

R=scheglov@google.com

Review URL: https://codereview.chromium.org//1447123002 .
diff --git a/CHANGELOG.md b/CHANGELOG.md
index a35ae95..3bf70cb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 0.1.6
+
+* Fix to `package_prefixed_library_names` (dart-lang/sdk#24947; #154).
+
 # 0.1.5
 
 * Added `prefer_is_not_empty` lint rule (#143).
diff --git a/lib/src/rules/package_prefixed_library_names.dart b/lib/src/rules/package_prefixed_library_names.dart
index 15f0e0c..da450ac 100644
--- a/lib/src/rules/package_prefixed_library_names.dart
+++ b/lib/src/rules/package_prefixed_library_names.dart
@@ -80,6 +80,11 @@
 
   @override
   visitLibraryDirective(LibraryDirective node) {
+    // If no project info is set, bail early.
+    // https://github.com/dart-lang/linter/issues/154
+    if (project == null) {
+      return;
+    }
     Source source = node.element.source;
     var prefix = createLibraryNamePrefix(
         libraryPath: source.fullName,
diff --git a/pubspec.yaml b/pubspec.yaml
index 6c2eb78..a89ecf6 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: linter
-version: 0.1.5
+version: 0.1.6
 author: Dart Team <misc@dartlang.org>
 description: Style linter for Dart.
 homepage: https://github.com/dart-lang/linter