Throw ArgumentError if packageRoot is null.

dart/pkg/compiler/lib/src/apiimpl.dart

 // Copyright (c) 2012, 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 leg_apiimpl;
 
 import 'dart:async';
 
 import '../compiler.dart' as api;
 import 'dart2jslib.dart' as leg;
@@ skipping 73 matching lines @@
             enableExperimentalMirrors:
                 hasOption(options, '--enable-experimental-mirrors'),
             enableAsyncAwait: hasOption(options, '--enable-async'),
             enableEnums: hasOption(options, '--enable-enum'),
             allowNativeExtensions:
                 hasOption(options, '--allow-native-extensions')) {
     tasks.addAll([
         userHandlerTask = new leg.GenericTask('Diagnostic handler', this),
         userProviderTask = new leg.GenericTask('Input provider', this),
     ]);
+    if (libraryRoot == null) {
+      throw new ArgumentError("[libraryRoot] is null.");
+    }
     if (!libraryRoot.path.endsWith("/")) {
-      throw new ArgumentError("libraryRoot must end with a /");
+      throw new ArgumentError("[libraryRoot] must end with a /.");
     }
-    if (packageRoot != null && !packageRoot.path.endsWith("/")) {
-      throw new ArgumentError("packageRoot must end with a /");
+    if (packageRoot == null) {
+      throw new ArgumentError("[packageRoot] is null.");
+    }
+    if (!packageRoot.path.endsWith("/")) {
+      throw new ArgumentError("[packageRoot] must end with a /.");
     }
     if (!analyzeOnly) {
       if (enableAsyncAwait) {
         throw new ArgumentError(
             "--enable-async is currently only supported with --analyze-only");
       }
       if (allowNativeExtensions) {
         throw new ArgumentError(
             "--allow-native-extensions is only supported in combination with "
             "--analyze-only");
@@ skipping 193 matching lines @@
     return libraryRoot.resolve(path);
   }
 
   Uri resolvePatchUri(String dartLibraryPath) {
     String patchPath = lookupPatchPath(dartLibraryPath);
     if (patchPath == null) return null;
     return libraryRoot.resolve(patchPath);
   }
 
   Uri translatePackageUri(leg.Spannable node, Uri uri) {
-    if (packageRoot == null) {
-      reportFatalError(
-          node, leg.MessageKind.PACKAGE_ROOT_NOT_SET, {'uri': uri});
-    }
     return packageRoot.resolve(uri.path);
   }
 
   Future<bool> run(Uri uri) {
     log('Allowed library categories: $allowedLibraryCategories');
     return super.run(uri).then((bool success) {
       int cumulated = 0;
       for (final task in tasks) {
         int elapsed = task.timing;
         if (elapsed != 0) {
@@ skipping 58 matching lines @@
     print('$message: ${tryToString(exception)}');
     print(tryToString(stackTrace));
   }
 
   fromEnvironment(String name) => environment[name];
 
   LibraryInfo lookupLibraryInfo(String libraryName) {
     return library_info.LIBRARIES[libraryName];
   }
 }