Support loading transformer plugins from pub.

sdk/lib/_internal/pub/lib/src/command.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 pub.command;
 
 import 'dart:io';
 import 'dart:async';
 
 import 'package:args/args.dart';
 import 'package:path/path.dart' as path;
+import 'package:stack_trace/stack_trace.dart';
 
 import 'command/cache.dart';
 import 'command/deploy.dart';
 import 'command/help.dart';
 import 'command/install.dart';
 import 'command/lish.dart';
 import 'command/list_package_dirs.dart';
 import 'command/serve.dart';
 import 'command/update.dart';
 import 'command/uploader.dart';
@@ skipping 61 matching lines @@
 
     cache = new SystemCache.withSources(cacheDir, isOffline: isOffline);
 
     handleError(error) {
       var trace = getAttachedStackTrace(error);
 
       // This is basically the top-level exception handler so that we don't
       // spew a stack trace on our users.
       var message;
 
-      try {
-        // Most exception types have a "message" property. We prefer this since
-        // it skips the "Exception:", "HttpException:", etc. prefix that calling
-        // toString() adds. But, alas, "message" isn't actually defined in the
-        // base Exception type so there's no easy way to know if it's available
-        // short of a giant pile of type tests for each known exception type.
-        //
-        // So just try it. If it throws, default to toString().
-        message = error.message;
-      } on NoSuchMethodError catch (_) {
-        message = error.toString();
-      }
-
-      log.error(message);
+      log.error(getErrorMessage(error));
 
       if (trace != null) {
         if (options['trace'] || !isUserFacingException(error)) {
-          log.error(trace);
+          log.error(new Trace.from(trace).terse);
         } else {
-          log.fine(trace);
+          log.fine(new Trace.from(trace).terse);
         }
       }
 
       if (options['trace']) {
         log.dumpTranscript();
       } else if (!isUserFacingException(error)) {
         log.error("""
 This is an unexpected error. Please run
 
     pub --trace ${new Options().arguments.map((arg) => "'$arg'").join(' ')}
@@ skipping 84 matching lines @@
   };
 
   for (var command in commands.values.toList()) {
     for (var alias in command.aliases) {
       commands[alias] = command;
     }
   }
 
   return commands;
 }