Fix typo in doc comment.

pkg/json_rpc_2/lib/error_code.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.
 
 /// Error codes defined in the [JSON-RPC 2.0 specificiation][spec].
 ///
 /// These codes are generally used for protocol-level communication. Most of
 /// them shouldn't be used by the application. Those that should have
 /// convenience constructors in [RpcException].
 ///
 /// [spec]: http://www.jsonrpc.org/specification#error_object
 library json_rpc_2.error_code;
 
 /// An error code indicating that invalid JSON was received by the server.
 const PARSE_ERROR = -32700;
 
 /// An error code indicating that the request JSON was invalid according to the
 /// JSON-RPC 2.0 spec.
 const INVALID_REQUEST = -32600;
 
 /// An error code indicating that the requested method does not exist or is
 /// unavailable.
 const METHOD_NOT_FOUND = -32601;
 
-/// An error code indicating that the request paramaters are invalid for the
+/// An error code indicating that the request parameters are invalid for the
 /// requested method.
 const INVALID_PARAMS = -32602;
 
 /// An internal JSON-RPC error.
 const INTERNAL_ERROR = -32603;
 
 /// An unexpected error occurred on the server.
 ///
 /// The spec reserves the range from -32000 to -32099 for implementation-defined
 /// server exceptions, but for now we only use one of those values.
 const SERVER_ERROR = -32000;