[Fix rubocop#12324] Fix an error for Layout/RescueEnsureAlignment

Fixes rubocop#12324.

This PR fixes an error for `Layout/RescueEnsureAlignment`
when using `rescue` in `do`...`end` block assigned to object attribute.

changelog/fix_error_for_layout_rescue_ensure_alignment.md

@@ -0,0 +1 @@
+* [#12324](https://github.com/rubocop/rubocop/issues/12324): Fix an error for `Layout/RescueEnsureAlignment` when using `rescue` in `do`...`end` block assigned to object attribute. ([@koic][])

lib/rubocop/cop/layout/rescue_ensure_alignment.rb

@@ -104,8 +104,8 @@ def alignment_source(node, starting_loc)
               mlhs_node, = *node
               mlhs_node.source_range
             else
-              # It is a wrapper with access modifier.
-              node.child_nodes.first.loc.name
+              # It is a wrapper with receiver of object attribute or access modifier.
+              node.receiver&.source_range || node.child_nodes.first.loc.name
             end
 
           range_between(starting_loc.begin_pos, ending_loc.end_pos).source

spec/rubocop/cop/layout/rescue_ensure_alignment_spec.rb

@@ -688,6 +688,23 @@ def foo
     end
   end
 
+  context 'rescue in do-end block assigned to object attribute' do
+    it 'registers an offense' do
+      expect_offense(<<~RUBY)
+        obj.attr = do_something do
+          rescue StandardError
+          ^^^^^^ `rescue` at 2, 2 is not aligned with `obj` at 1, 0.
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        obj.attr = do_something do
+        rescue StandardError
+        end
+      RUBY
+    end
+  end
+
   context 'rescue in do-end block on multi-assignment' do
     it 'registers an offense' do
       expect_offense(<<~RUBY)