Handle bad regexs in search.findTopLevelDeclarations.

pkg/analysis_server/test/search/top_level_declarations_test.dart

Index: pkg/analysis_server/test/search/top_level_declarations_test.dart
diff --git a/pkg/analysis_server/test/search/top_level_declarations_test.dart b/pkg/analysis_server/test/search/top_level_declarations_test.dart
index 81fa08b749478c62191201a78d2db826a4988f2f..e9be56a3bdeda094feda10c81aafa93e27d9c7a0 100644
--- a/pkg/analysis_server/test/search/top_level_declarations_test.dart
+++ b/pkg/analysis_server/test/search/top_level_declarations_test.dart
@@ -39,6 +39,9 @@ class TopLevelDeclarationsTest extends AbstractSearchDomainTest {
     Request request =
         new SearchFindTopLevelDeclarationsParams(pattern).toRequest('0');
     Response response = await waitResponse(request);
+    if (response.error != null) {
+      return response.error;
+    }
     searchId =
         new SearchFindTopLevelDeclarationsResult.fromResponse(response).id;
     return waitForSearchResults();
@@ -63,6 +66,7 @@ D() {}
 var E = null;
 class ABC {}
 ''');
+
     await findTopLevelDeclarations('^[A-E]\$');
     assertHasDeclaration(ElementKind.CLASS, 'A');
     assertHasDeclaration(ElementKind.CLASS, 'B');
@@ -71,4 +75,9 @@ class ABC {}
     assertHasDeclaration(ElementKind.TOP_LEVEL_VARIABLE, 'E');
     assertNoDeclaration(ElementKind.CLASS, 'ABC');
   }
+
+  test_invalidRegex() async {
+    var result = await findTopLevelDeclarations('[A');
+    expect(result, new isInstanceOf<RequestError>());
+  }
 }