Merge pull request #9375 from koic/fix_error_for_style_if_inside_else

[Fix #9372] Fix an error for `Style/IfInsideElse`

changelog/fix_error_for_style_if_inside_else.md

@@ -0,0 +1 @@
+* [#9372](https://github.com/rubocop-hq/rubocop/issues/9372): Fix an error for `Style/IfInsideElse` when nested `if` branch code is empty. ([@koic][])

lib/rubocop/cop/style/if_inside_else.rb

@@ -86,9 +86,10 @@ def autocorrect(corrector, node)
             correct_to_elsif_from_if_inside_else_form(corrector, node, node.condition)
           end
           corrector.remove(range_by_whole_lines(find_end_range(node), include_final_newline: true))
-          corrector.remove(
-            range_by_whole_lines(node.if_branch.source_range, include_final_newline: true)
-          )
+          return unless (if_branch = node.if_branch)
+
+          range = range_by_whole_lines(if_branch.source_range, include_final_newline: true)
+          corrector.remove(range)
         end
 
         def correct_to_elsif_from_modifier_form(corrector, node)
@@ -101,10 +102,12 @@ def correct_to_elsif_from_modifier_form(corrector, node)
 
         def correct_to_elsif_from_if_inside_else_form(corrector, node, condition)
           corrector.replace(node.parent.loc.else, "elsif #{condition.source}")
-          if_condition_range = range_between(
-            node.loc.keyword.begin_pos, condition.source_range.end_pos
-          )
-          corrector.replace(if_condition_range, node.if_branch.source)
+          if_condition_range = if_condition_range(node, condition)
+          if (if_branch = node.if_branch)
+            corrector.replace(if_condition_range, if_branch.source)
+          else
+            corrector.remove(range_by_whole_lines(if_condition_range, include_final_newline: true))
+          end
           corrector.remove(condition)
         end
 
@@ -115,6 +118,10 @@ def find_end_range(node)
           find_end_range(node.parent)
         end
 
+        def if_condition_range(node, condition)
+          range_between(node.loc.keyword.begin_pos, condition.source_range.end_pos)
+        end
+
         def allow_if_modifier_in_else_branch?(else_branch)
           allow_if_modifier? && else_branch&.modifier_form?
         end

spec/rubocop/cop/style/if_inside_else_spec.rb

@@ -51,6 +51,31 @@
     RUBY
   end
 
+  it 'catches an `if..else` nested inside an `else` and nested inside `if` branch code is empty' do
+    expect_offense(<<~RUBY)
+      if a
+        foo
+      else
+        if b
+        ^^ Convert `if` nested inside `else` to `elsif`.
+          # TODO: comment.
+        else
+          bar
+        end
+      end
+    RUBY
+
+    expect_correction(<<~RUBY)
+      if a
+        foo
+      elsif b
+          # TODO: comment.
+        else
+          bar
+      end
+    RUBY
+  end
+
   it 'catches an if..elsif..else nested inside an else' do
     expect_offense(<<~RUBY)
       if a