Fix an error for Naming/ConstantName

Fixes rubocop#8422 (comment).

This PR fixes an error for `Naming/ConstantName`
when assigning a constant from an empty branch of `else`.

changelog/fix_a_false_positive_for_naming_constant_name.md

@@ -0,0 +1 @@
+* [#11865](https://github.com/rubocop/rubocop/pull/11865): Fix an error for `Naming/ConstantName` when assigning a constant from an empty branch of `else`. ([@koic][])

lib/rubocop/cop/naming/constant_name.rb

@@ -76,7 +76,7 @@ def allowed_conditional_expression_on_rhs?(node)
         end
 
         def contains_constant?(node)
-          node.branches.any?(&:const_type?)
+          node.branches.compact.any?(&:const_type?)
         end
       end
     end

spec/rubocop/cop/naming/constant_name_spec.rb

@@ -114,6 +114,15 @@
     RUBY
   end
 
+  it 'does not register an offense when assigning a constant from an empty branch of `else`' do
+    expect_no_offenses(<<~RUBY)
+      CONST = if condition
+        foo
+      else
+      end
+    RUBY
+  end
+
   context 'when a rhs is a conditional expression' do
     context 'when conditional branches contain only constants' do
       it 'does not check names' do