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sdk/lib/_internal/pub/lib/src/source_registry.dart

Index: sdk/lib/_internal/pub/lib/src/source_registry.dart
diff --git a/sdk/lib/_internal/pub/lib/src/source_registry.dart b/sdk/lib/_internal/pub/lib/src/source_registry.dart
index 6dbe58e9625725348af8bff81f53c603d88dd74b..cd3dc3ef162cbd46ccfcd330ded435c71a505897 100644
--- a/sdk/lib/_internal/pub/lib/src/source_registry.dart
+++ b/sdk/lib/_internal/pub/lib/src/source_registry.dart
@@ -43,6 +43,8 @@ class SourceRegistry {
 
   /// Returns the source named [name]. Throws an error if no such source has
   /// been registered. If [name] is null, returns the default source.
+  // TODO(rnystrom): Return a NullSource that does nothing safely so that
+  // calling code doesn't have to worry about it.
   Source operator[](String name) {
     if (name == null) {
       if (defaultSource != null) return defaultSource;