Fix SystemStackError caused by infinite recursion in _handle_result

When an error occurred during result handling (e.g., a logging error),
the rescue block in _handle_result would recursively call itself,
leading to infinite recursion and SystemStackError.

This fix prevents recursion by directly invoking the error callbacks
instead of calling _handle_result again. The logger.error call is also
wrapped with rescue nil to prevent logging errors from propagating.

Fixes #12

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: dblock

.rubocop_todo.yml

@@ -1,15 +1,14 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2025-07-05 14:01:58 UTC using RuboCop version 1.77.0.
+# on 2026-01-29 18:49:42 UTC using RuboCop version 1.84.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
 # Offense count: 1
-# Configuration parameters: EnforcedStyle, AllowedGems, Include.
+# Configuration parameters: EnforcedStyle, AllowedGems.
 # SupportedStyles: Gemfile, gems.rb, gemspec
-# Include: **/*.gemspec, **/Gemfile, **/gems.rb
 Gemspec/DevelopmentDependencies:
   Exclude:
     - 'ruby-link-checker.gemspec'
@@ -36,9 +35,20 @@ Layout/EmptyLineAfterMagicComment:
     - 'spec/ruby-link-checker/checker_spec.rb'
     - 'spec/ruby-link-checker/config_spec.rb'
 
+# Offense count: 4
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: native, lf, crlf
+Layout/EndOfLine:
+  Exclude:
+    - 'lib/ruby-link-checker/logger.rb'
+    - 'spec/ruby-link-checker/checker_spec.rb'
+    - 'spec/ruby-link-checker/config_spec.rb'
+    - 'spec/spec_helper.rb'
+
 # Offense count: 3
 # This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: Width, AllowedPatterns.
+# Configuration parameters: Width, EnforcedStyleAlignWith, AllowedPatterns.
+# SupportedStylesAlignWith: start_of_line, relative_to_receiver
 Layout/IndentationWidth:
   Exclude:
     - 'spec/ruby-link-checker/checker_spec.rb'
@@ -141,7 +151,7 @@ RSpec/EmptyLineAfterExample:
   Exclude:
     - 'spec/ruby-link-checker/config_spec.rb'
 
-# Offense count: 13
+# Offense count: 14
 # Configuration parameters: CountAsOne.
 RSpec/ExampleLength:
   Max: 9
@@ -191,16 +201,17 @@ RSpec/NamedSubject:
 RSpec/NestedGroups:
   Max: 6
 
-# Offense count: 6
-# Configuration parameters: Include, CustomTransform, IgnoreMethods, IgnoreMetadata.
-# Include: **/*_spec.rb
+# Offense count: 7
+# Configuration parameters: CustomTransform, IgnoreMethods, IgnoreMetadata, InflectorPath, EnforcedInflector.
+# SupportedInflectors: default, active_support
 RSpec/SpecFilePathFormat:
   Exclude:
     - '**/spec/routing/**/*'
     - 'spec/ruby-link-checker/callbacks_spec.rb'
     - 'spec/ruby-link-checker/checker_spec.rb'
     - 'spec/ruby-link-checker/config_spec.rb'
     - 'spec/ruby-link-checker/net/http/checker_spec.rb'
+    - 'spec/ruby-link-checker/tasks_spec.rb'
     - 'spec/ruby-link-checker/typhoeus/hydra/checker_spec.rb'
     - 'spec/ruby-link-checker/version_spec.rb'
 
@@ -307,6 +318,12 @@ Style/NumericPredicate:
     - 'spec/**/*'
     - 'lib/ruby-link-checker/tasks.rb'
 
+# Offense count: 1
+# This cop supports safe autocorrection (--autocorrect).
+Style/RescueModifier:
+  Exclude:
+    - 'lib/ruby-link-checker/tasks.rb'
+
 # Offense count: 1
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: Mode.
@@ -344,7 +361,7 @@ Style/SuperWithArgsParentheses:
 
 # Offense count: 1
 # This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: AllowHeredoc, AllowURI, AllowQualifiedName, URISchemes, IgnoreCopDirectives, AllowedPatterns, SplitStrings.
+# Configuration parameters: AllowHeredoc, AllowURI, AllowQualifiedName, URISchemes, AllowRBSInlineAnnotation, AllowCopDirectives, AllowedPatterns, SplitStrings.
 # URISchemes: http, https
 Layout/LineLength:
   Max: 123

CHANGELOG.md

@@ -1,5 +1,6 @@
 ### 0.3.1 (Next)
 
+* [#13](https://github.com/dblock/ruby-link-checker/pull/13): Fix `SystemStackError` caused by infinite recursion in `_handle_result` - [@dblock](https://github.com/dblock), [@Copilot](https://github.com/Copilot).
 * [#14](https://github.com/dblock/ruby-link-checker/pull/14): Migrate Danger to use danger-pr-comment workflow - [@dblock](https://github.com/dblock), [@Copilot](https://github.com/Copilot).
 * [#14](https://github.com/dblock/ruby-link-checker/pull/14): Removed Code Climate - [@dblock](https://github.com/dblock), [@Copilot](https://github.com/Copilot).
 * [#15](https://github.com/dblock/ruby-link-checker/pull/15): Added Codecov - [@dblock](https://github.com/dblock), [@Copilot](https://github.com/Copilot).

lib/ruby-link-checker/tasks.rb

@@ -103,8 +103,10 @@ def _handle_result(result)
         execute!
       end
     rescue StandardError => e
-      logger.error("#{self}##{__method__}") { e }
-      _handle_result ResultError.new(result.uri, result.method, result.result_uri, e, options)
+      logger.error("#{self}##{__method__}") { e } rescue nil
+      error_result = ResultError.new(result.uri, result.method, result.result_uri, e, options)
+      result! error_result
+      error! error_result
     end
   end
 end

spec/ruby-link-checker/tasks_spec.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe LinkChecker::Tasks do
+  describe '#_handle_result' do
+    # Reproduces issue #12: SystemStackError when logging causes repeated errors
+    # https://github.com/dblock/ruby-link-checker/issues/12
+    context 'when logger.info raises an error repeatedly' do
+      let(:checker) { LinkChecker::Net::HTTP::Checker.new(methods: ['GET']) }
+      let(:task_klass) { LinkChecker::Net::HTTP::Task }
+      let(:url) { 'https://www.example.org' }
+
+      before do
+        stub_request(:get, url).to_return(status: 200, body: '', headers: {})
+      end
+
+      it 'does not cause infinite recursion leading to SystemStackError' do
+        tasks = described_class.new(checker, task_klass, url, ['GET'])
+
+        # Stub logger to always raise an error on info, simulating the scenario
+        # from issue #12 where logging causes a stack overflow due to the
+        # rescue block in _handle_result recursively calling itself
+        allow(tasks).to receive(:logger).and_return(
+          instance_double(LinkChecker::Logger).tap do |logger|
+            allow(logger).to receive(:info).and_raise(StandardError, 'stack level too deep')
+            allow(logger).to receive(:error)
+          end
+        )
+
+        # Should not raise SystemStackError - the error should be handled gracefully
+        expect { tasks.execute! }.not_to raise_error
+      end
+    end
+  end
+end