CQ. Fix for not-implemented exception in ExitDetector for NullAwareElement.

Saw a crash in logs: StateError: Bad state: Missing a visit method for a node of type NullAwareElementImpl at ExitDetector.visitNode	(exit_detector.dart:457) at GeneralizingAstVisitor.visitCatchClause	(visitor.g.dart:89) at GeneralizingAstVisitor.visitExpression	(visitor.g.dart:216) at NullAwareElementImpl.accept	(ast.dart:17535) at _extension#1.terminatesControl	(use_build_context_synchronously.dart:1377) at AsyncStateVisitor._visitIfLike	(use_build_context_synchronously.dart:857) at AsyncStateVisitor.visitIfStatement	(use_build_context_synchronously.dart:426) at IfElementImpl.accept	(ast.dart:12479) at AsyncStateVisitor._asynchronousIfAnyIsAsync.<fn>	(use_build_context_synchronously.dart:682) Change-Id: Idf79a71b33411eba63b2a01b22d1f18b89fbeac4 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/456111 Reviewed-by: Johnni Winther <johnniwinther@google.com> Commit-Queue: Konstantin Shcheglov <scheglov@google.com>

Author: scheglov

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

@@ -475,6 +475,11 @@ class ExitDetector extends GeneralizingAstVisitor<bool> {
  );
  }
 
+ @override
+ bool? visitNullAwareElement(NullAwareElement node) {
+ return _nodeExits(node.value);
+ }
+
  @override
  bool visitParenthesizedExpression(ParenthesizedExpression node) =>
  node.expression.accept(this)!;

pkg/analyzer/test/src/dart/resolver/exit_detector_test.dart

@@ -108,6 +108,10 @@ class ExitDetectorForCodeAsUiTest extends ParseBase {
  _assertFalse('[if (c) throw 42 else 0]');
  }
 
+ test_nullAwareElement() async {
+ _assertFalse('[?0]');
+ }
+
  void _assertFalse(String expressionCode) {
  _assertHasReturn(expressionCode, false);
  }