Fix typo and update handling of error.
diff --git a/lib/src/chain.dart b/lib/src/chain.dart
index e93b2b4..08aabb0 100644
--- a/lib/src/chain.dart
+++ b/lib/src/chain.dart
@@ -93,7 +93,8 @@
         return callback();
       } catch (error, stackTrace) {
         // TODO(nweiz): Don't special-case this when issue 19566 is fixed.
-        return Zone.current.handleUncaughtError(error, stackTrace);
+        Zone.current.handleUncaughtError(error, stackTrace);
+        return null;
       }
     },
         zoneSpecification: spec.toSpec(),
diff --git a/lib/src/stack_zone_specification.dart b/lib/src/stack_zone_specification.dart
index 53ab775..f71f610 100644
--- a/lib/src/stack_zone_specification.dart
+++ b/lib/src/stack_zone_specification.dart
@@ -102,7 +102,7 @@
   /// Tracks the current stack chain so it can be set to [_currentChain] when
   /// [f] is run.
   ZoneUnaryCallback<R, T> _registerUnaryCallback<R, T>(
-      Zone self, ZoneDelegate parent, Zone zone, R f(T arg) {
+      Zone self, ZoneDelegate parent, Zone zone, R f(T arg)) {
     if (f == null || _disabled) return parent.registerUnaryCallback(zone, f);
     var node = _createNode(1);
     return parent.registerUnaryCallback(zone, (arg) {