NPE fix in ExitDetector visitor- in analyzer pkg

pkg/analyzer/lib/src/generated/resolver.dart

Index: pkg/analyzer/lib/src/generated/resolver.dart
diff --git a/pkg/analyzer/lib/src/generated/resolver.dart b/pkg/analyzer/lib/src/generated/resolver.dart
index 123ceadbcbcabce8b70fc9d0aa72a297b822f260..02781e4e70f4c8839152e05ebf97a94ac3b83b52 100644
--- a/pkg/analyzer/lib/src/generated/resolver.dart
+++ b/pkg/analyzer/lib/src/generated/resolver.dart
@@ -3907,6 +3907,10 @@ class ExitDetector extends GeneralizingAstVisitor<bool> {
       _nodeExits(node.leftHandSide) || _nodeExits(node.rightHandSide);
 
   @override
+  bool visitAwaitExpression(AwaitExpression node) =>
+      _nodeExits(node.expression);
+
+  @override
   bool visitBinaryExpression(BinaryExpression node) {
     Expression lhsExpression = node.leftOperand;
     sc.TokenType operatorType = node.operator.type;