fix: update avoid_unnecessary_return_variable

lib/src/lints/avoid_unnecessary_return_variable/visitors/avoid_unnecessary_return_variable_visitor.dart

@@ -15,15 +15,16 @@ class AvoidUnnecessaryReturnVariableVisitor extends SimpleAstVisitor<void> {
 
   @override
   void visitReturnStatement(ReturnStatement node) {
-    final expr = node.expression;
+    final expr = node.expression?.unParenthesized;
     if (expr is! SimpleIdentifier) return;
 
     final element = expr.element;
     if (element is! LocalVariableElement) return;
 
     if (!element.isFinal && !element.isConst) return;
 
-    final block = node.parent;
+    //get enclosing block function body
+    final block = node.thisOrAncestorOfType<BlockFunctionBody>()?.block;
     if (block == null) return;
 
     final returnVariableUsageVisitor = ReturnVariableUsageVisitor(
@@ -34,16 +35,18 @@ class AvoidUnnecessaryReturnVariableVisitor extends SimpleAstVisitor<void> {
     block.visitChildren(returnVariableUsageVisitor);
     if (!returnVariableUsageVisitor.hasBadStatementCount) return;
 
+    //check if declaration statement is found
+    final declaration = returnVariableUsageVisitor.variableDeclaration;
+    if (declaration == null) return;
+
     //it is 100% bad if return statement follows declaration
     if (!returnVariableUsageVisitor.foundTokensBetweenDeclarationAndReturn) {
       _rule.reportAtNode(node);
       return;
     }
 
-    final declaration = returnVariableUsageVisitor.variableDeclaration;
-
     //check if immutable
-    final initializer = declaration?.initializer;
+    final initializer = declaration.initializer;
     if (initializer == null) return;
 
     if (!_isExpressionImmutable(initializer)) return;

test/lints/avoid_unnecessary_return_variable/avoid_unnecessary_return_variable_rule_test.dart

@@ -172,4 +172,44 @@ void _doNothing() {}
       [lint(304, 14)],
     );
   }
+
+  void test_does_not_report_if_return_is_cached_nested_block() async {
+    await assertNoDiagnostics(r'''
+Future<String?> testAvoidUnnecessaryReturnVariableNestedBlock() async {
+  final cached = 'cached';
+  if (cached.isNotEmpty) {
+    // Should NOT trigger the avoid_unnecessary_return_variable lint
+    return cached;
+  }
+  return null;
+}
+''');
+  }
+
+  void test_reports_if_return_is_cached_and_only_returned_nested_block() async {
+    await assertDiagnostics(
+      r'''
+int test(bool b) {
+  final a = 3;
+  if (b) {
+    return a;
+  }
+  return 0;
+}
+''',
+      [lint(49, 9)],
+    );
+  }
+
+  void test_reports_if_return_in_parentheses() async {
+    await assertDiagnostics(
+      r'''
+int test() {
+  final a = 3;
+  return (a);
+}
+''',
+      [lint(30, 11)],
+    );
+  }
 }