Issue 21238. Fix for NPE in occurrences computer when FieldFormalParameterElement references unreso…

pkg/analysis_server/test/analysis/notification_occurrences_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library test.analysis.notification.occurrences;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/constants.dart';
 import 'package:analysis_server/src/protocol.dart';
@@ skipping 118 matching lines @@
 ''');
     return prepareOccurrences().then((_) {
       assertHasRegion('fff;');
       expect(testOccurences.element.kind, ElementKind.FIELD);
       assertHasOffset('fff); // constructor');
       assertHasOffset('fff = 42;');
       assertHasOffset('fff); // print');
     });
   }
 
+  test_field_unresolved() {
+    addTestFile('''
+class A {
+  A(this.noSuchField);
+}
+''');
+    // no checks for occurrences, just ensure that there is no NPE
+    return prepareOccurrences();
+  }
+
   test_localVariable() {
     addTestFile('''
 main() {
   var vvv = 42;
   vvv += 5;
   print(vvv);
 }
 ''');
     return prepareOccurrences().then((_) {
       assertHasRegion('vvv =');
@@ skipping 99 matching lines @@
     addTestFile('''
 void main() {
 }
 ''');
     return prepareOccurrences().then((_) {
       int offset = findOffset('void main()');
       findRegion(offset, 'void'.length, false);
     });
   }
 }