Temp fix to allow plugins to serve the getErrors APIs.

pkg/analysis_server/lib/src/domain_analysis.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 domain.analysis;
 
 import 'dart:async';
 import 'dart:core';
 
 import 'package:analysis_server/plugin/analysis/analysis_domain.dart';
@@ skipping 49 matching lines @@
       } else {
         List<AnalysisError> protocolErrors =
             doAnalysisError_listFromEngine(analysisOptions, lineInfo, errors);
         server.sendResponse(
             new AnalysisGetErrorsResult(protocolErrors).toResponse(request.id));
       }
     }
 
     if (server.options.enableNewAnalysisDriver) {
       var result = await server.getAnalysisResult(file);
+
+      if (server.onResultErrorSupplementor != null) {
+        if (result != null) {
+          await server.onResultErrorSupplementor(file, result.errors);
+        } else {
+          server.onNoAnalysisResult(file, send);
+          return;
+        }
+      }
+
       send(result?.driver?.analysisOptions, result?.lineInfo, result?.errors);
       return;
     }
 
     Future<AnalysisDoneReason> completionFuture =
         server.onFileAnalysisComplete(file);
     if (completionFuture == null) {
       server.sendResponse(new Response.getErrorsInvalidFile(request));
     }
     completionFuture.then((AnalysisDoneReason reason) async {
@@ skipping 361 matching lines @@
       context.onResultChanged(descriptor).listen((result) {
         StreamController<engine.ResultChangedEvent> controller =
             controllers[result.descriptor];
         if (controller != null) {
           controller.add(result);
         }
       });
     }
   }
 }