[Fix #287] don't error on empty blocks when linting assert_raises

Author: G-Rath

changelog/fix_don_t_error_on_empty_blocks_when_linting.md

@@ -0,0 +1 @@
+* [#287](https://github.com/rubocop/rubocop-minitest/issues/287): Don't error on empty blocks when linting `assert_raises`. ([@G-Rath][])

lib/rubocop/cop/minitest/assert_raises_compound_body.rb

@@ -37,7 +37,7 @@ def on_block(node) # rubocop:disable InternalAffairs/NumblockHandler
         private
 
         def multi_statement_begin?(node)
-          node.begin_type? && node.children.size > 1
+          node&.begin_type? && node.children.size > 1
         end
       end
     end

test/rubocop/cop/minitest/assert_raises_compound_body_test.rb

@@ -13,6 +13,14 @@ def test_registers_offense_when_multi_statement_bodies
     RUBY
   end
 
+  def test_does_not_register_offense_when_empty_bodies
+    assert_no_offenses(<<~RUBY)
+      assert_raises(MyError) do
+        # nothing to see here...
+      end
+    RUBY
+  end
+
   def test_does_not_register_offense_when_single_statement_bodies
     assert_no_offenses(<<~RUBY)
       assert_raises(MyError) do