Include reasons for failing in StateError.

dart/site/try/poi/poi.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 trydart.poi;
 
 import 'dart:async' show
     Completer,
     Future;
 
@@ skipping 379 matching lines @@
   ];
 
   if (!isCompiler) {
     options.add('--analyze-only');
   }
 
   if (enableMinification) {
     options.add('--minify');
   }
 
-  LibraryUpdater updater =
-      new LibraryUpdater(
-          cachedCompiler, inputProvider, script, printWallClock, printVerbose);
+  LibraryUpdater updater;
+
   Future<bool> reuseLibrary(LibraryElement library) {
     return poiTask.measure(() => updater.reuseLibrary(library));
   }
 
-  return reuseCompiler(
-      diagnosticHandler: handler,
-      inputProvider: inputProvider,
-      options: options,
-      cachedCompiler: cachedCompiler,
-      libraryRoot: libraryRoot,
-      packageRoot: packageRoot,
-      packagesAreImmutable: true,
-      reuseLibrary: reuseLibrary).then((Compiler newCompiler) {
+  Future<Compiler> invokeReuseCompiler() {
+    updater = new LibraryUpdater(
+        cachedCompiler, inputProvider, script, printWallClock, printVerbose);
+    return reuseCompiler(
+        diagnosticHandler: handler,
+        inputProvider: inputProvider,
+        options: options,
+        cachedCompiler: cachedCompiler,
+        libraryRoot: libraryRoot,
+        packageRoot: packageRoot,
+        packagesAreImmutable: true,
+        reuseLibrary: reuseLibrary);
+  }
+
+  return invokeReuseCompiler().then((Compiler newCompiler) {
+    // TODO(ahe): Move this "then" block to [reuseCompiler].
+    if (updater.failed) {
+      cachedCompiler = null;
+      return invokeReuseCompiler();
+    } else {
+      return newCompiler;
+    }
+  }).then((Compiler newCompiler) {
     if (!isCompiler) {
       newCompiler.enqueuerFilter = new ScriptOnlyFilter(script);
     }
     return runPoiInternal(newCompiler, sw, updater, position);
   });
 }
 
 Future<Element> runPoiInternal(
     Compiler newCompiler,
     Stopwatch sw,
@@ skipping 357 matching lines @@
 
 modelx.ImportScope importScope(modelx.LibraryElementX element) {
   return element.importScope;
 }
 
 class PoiTask extends CompilerTask {
   PoiTask(Compiler compiler) : super(compiler);
 
   String get name => 'POI';
 }