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

pkg/analysis_server/test/analysis/notification_occurrences_test.dart

Index: pkg/analysis_server/test/analysis/notification_occurrences_test.dart
diff --git a/pkg/analysis_server/test/analysis/notification_occurrences_test.dart b/pkg/analysis_server/test/analysis/notification_occurrences_test.dart
index 34fcac71b031256b91031392da919f220dd5ece8..7daf84dbedfb07331ef8c0f404bb91b2c3728df1 100644
--- a/pkg/analysis_server/test/analysis/notification_occurrences_test.dart
+++ b/pkg/analysis_server/test/analysis/notification_occurrences_test.dart
@@ -136,6 +136,16 @@ class A {
     });
   }
 
+  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() {