Fix the error response for bad isolate ids, etc.

runtime/vm/service/vmservice.dart

 // Copyright (c) 2013, 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 vmservice;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:isolate';
 import 'dart:typed_data';
 
 part 'client.dart';
 part 'constants.dart';
 part 'running_isolate.dart';
 part 'running_isolates.dart';
 part 'message.dart';
 part 'message_router.dart';
 
 final RawReceivePort isolateLifecyclePort = new RawReceivePort();
 final RawReceivePort scriptLoadPort = new RawReceivePort();
 
 typedef ShutdownCallback();
 
+// These must be kept in sync with the declarations in vm/json_stream.h.
+const kInvalidParams = -32602;
+const kInternalError = -32603;
+const kStreamAlreadySubscribed = 103;
+const kStreamNotSubscribed = 104;
+
+var _errorMessages = {
+  kInvalidParams: 'Invalid params',
+  kInternalError: 'Internal error',
+  kStreamAlreadySubscribed: 'Stream already subscribed',
+  kStreamNotSubscribed: 'Stream not subscribed',
+};
+
+String encodeRpcError(Message message, int code, {String details}) {
+  var response = {
+    'jsonrpc': '2.0',
+    'id' : message.serial,
+    'error' : {
+      'code': code,
+      'message': _errorMessages[code],
+    },
+  };
+  if (details != null) {
+    response['error']['data'] = {
+      'details': details,
+    };
+  }
+  return JSON.encode(response);
+}
+
 class VMService extends MessageRouter {
   static VMService _instance;
 
   /// Collection of currently connected clients.
   final Set<Client> clients = new Set<Client>();
 
   /// Collection of currently running isolates.
   RunningIsolates runningIsolates = new RunningIsolates();
 
   /// A port used to receive events from the VM.
@@ skipping 102 matching lines @@
     var members = [];
     var result = {};
     clients.forEach((client) {
       members.add(client.toJson());
     });
     result['type'] = 'ClientList';
     result['members'] = members;
     message.setResponse(JSON.encode(result));
   }
 
-  // These must be kept in sync with the declarations in vm/json_stream.h.
-  static const _kInvalidParams = -32602;
-  static const _kStreamAlreadySubscribed = 103;
-  static const _kStreamNotSubscribed = 104;
-
-  var _errorMessages = {
-    _kInvalidParams: 'Invalid params"',
-    _kStreamAlreadySubscribed: 'Stream already subscribed',
-    _kStreamNotSubscribed: 'Stream not subscribed',
-  };
-
-  String _encodeError(Message message, int code, {String details}) {
-    var response = {
-      'jsonrpc': '2.0',
-      'id' : message.serial,
-      'error' : {
-        'code': code,
-        'message': _errorMessages[code],
-      },
-    };
-    if (details != null) {
-      response['error']['data'] = {
-        'details': details,
-      };
-    }
-    return JSON.encode(response);
-  }
-
   String _encodeResult(Message message, Map result) {
     var response = {
       'jsonrpc': '2.0',
       'id' : message.serial,
       'result' : result,
     };
     return JSON.encode(response);
   }
 
   bool _isAnyClientSubscribed(String streamId) {
     for (var client in clients) {
       if (client.streams.contains(streamId)) {
         return true;
       }
     }
     return false;
   }
 
   Future<String> _streamListen(Message message) async {
     var client = message.client;
     var streamId = message.params['streamId'];
 
     if (client.streams.contains(streamId)) {
-      return _encodeError(message, _kStreamAlreadySubscribed);
+      return encodeRpcError(message, kStreamAlreadySubscribed);
     }
     if (!_isAnyClientSubscribed(streamId)) {
       if (!_vmListenStream(streamId)) {
-        return _encodeError(
-            message, _kInvalidParams,
+        return encodeRpcError(
+            message, kInvalidParams,
             details:"streamListen: invalid 'streamId' parameter: ${streamId}");
       }
     }
     client.streams.add(streamId);
 
     var result = { 'type' : 'Success' };
     return _encodeResult(message, result);
   }
 
   Future<String> _streamCancel(Message message) async {
     var client = message.client;
     var streamId = message.params['streamId'];
 
     if (!client.streams.contains(streamId)) {
-      return _encodeError(message, _kStreamNotSubscribed);
+      return encodeRpcError(message, kStreamNotSubscribed);
     }
     client.streams.remove(streamId);
     if (!_isAnyClientSubscribed(streamId)) {
       _vmCancelStream(streamId);
     }
 
     var result = { 'type' : 'Success' };
     return _encodeResult(message, result);
   }
 
@@ skipping 90 matching lines @@
   service.runningIsolates.isolateStartup(port_id, sp, name);
 }
 
 void _onStart() native "VMService_OnStart";
 
 void _onExit() native "VMService_OnExit";
 
 bool _vmListenStream(String streamId) native "VMService_ListenStream";
 
 void _vmCancelStream(String streamId) native "VMService_CancelStream";