Fix an error for Style/SelectByRegexp

changelog/fix_error_for_style_select_by_regexp.md

@@ -0,0 +1 @@
+* [#11348](https://github.com/rubocop/rubocop/pull/11348): Fix an error for `Style/SelectByRegexp` when block body is empty. ([@koic][])

lib/rubocop/cop/style/select_by_regexp.rb

@@ -86,12 +86,12 @@ class SelectByRegexp < Base
 
         def on_send(node)
           return unless (block_node = node.block_node)
-          return if block_node.body.begin_type?
+          return if block_node.body&.begin_type?
           return if receiver_allowed?(block_node.receiver)
           return unless (regexp_method_send_node = extract_send_node(block_node))
           return if match_predicate_without_receiver?(regexp_method_send_node)
 
-          opposite = regexp_method_send_node.send_type? && regexp_method_send_node.method?(:!~)
+          opposite = opposite?(regexp_method_send_node)
           regexp = find_regexp(regexp_method_send_node, block_node)
 
           register_offense(node, block_node, regexp, opposite)
@@ -128,6 +128,10 @@ def extract_send_node(block_node)
           regexp_method_send_node
         end
 
+        def opposite?(regexp_method_send_node)
+          regexp_method_send_node.send_type? && regexp_method_send_node.method?(:!~)
+        end
+
         def find_regexp(node, block)
           return node.child_nodes.first if node.match_with_lvasgn_type?
 

spec/rubocop/cop/style/select_by_regexp_spec.rb

@@ -150,6 +150,12 @@
         RUBY
       end
 
+      it 'does not register an offense when the block body is empty' do
+        expect_no_offenses(<<~RUBY)
+          array.#{method} { }
+        RUBY
+      end
+
       it 'registers an offense and corrects without a receiver' do
         expect_offense(<<~RUBY, method: method)
           #{method} { |x| x.match?(/regexp/) }