pkg/shelf: handle errors when parsing HttpRequest in shelf_io

pkg/shelf/lib/shelf_io.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.
 
 /// A Shelf adapter for handling [HttpRequest] objects from `dart:io`.
 ///
 /// One can provide an instance of [HttpServer] as the `requests` parameter in
 /// [serveRequests].
 ///
 /// The `dart:io` adapter supports request hijacking; see [Request.hijack].
@@ skipping 35 matching lines @@
     requests.listen((request) => handleRequest(request, handler));
   }, (error, stackTrace) {
     _logError('Asynchronous error\n$error', stackTrace);
   });
 }
 
 /// Uses [handler] to handle [request].
 ///
 /// Returns a [Future] which completes when the request has been handled.
 Future handleRequest(HttpRequest request, Handler handler) {
-  var shelfRequest = _fromHttpRequest(request);
+  var shelfRequest;
+  try {
+    shelfRequest = _fromHttpRequest(request);
+  } catch (error, stackTrace) {
+    var response = _logError('Error parsing request.\n$error', stackTrace);
+    return _writeResponse(response, request.response);
+  }
 
   // TODO(nweiz): abstract out hijack handling to make it easier to implement an
   // adapter.
   return syncFuture(() => handler(shelfRequest))
       .catchError((error, stackTrace) {
     if (error is HijackException) {
       // A HijackException should bypass the response-writing logic entirely.
       if (!shelfRequest.canHijack) throw error;
 
       // If the request wasn't hijacked, we shouldn't be seeing this exception.
@@ skipping 71 matching lines @@
   }
   chain = chain
       .foldFrames((frame) => frame.isCore || frame.package == 'shelf')
       .terse;
 
   stderr.writeln('ERROR - ${new DateTime.now()}');
   stderr.writeln(message);
   stderr.writeln(chain);
   return new Response.internalServerError();
 }