Fix Podfile issue #24342 (#25079)

* Fix Podfile issue #24342

Sometimes base configurations  (config.base_configuration_reference) can be nil, which leads to undefined method `real_path' for nil:NilClass.

* Disable bitcode in every case

packages/flutter_tools/templates/module/ios/library/Flutter.tmpl/podhelper.rb

@@ -65,6 +65,7 @@ post_install do |installer|
     installer.pods_project.targets.each do |target|
         target.build_configurations.each do |config|
             config.build_settings['ENABLE_BITCODE'] = 'NO'
+            next if  config.base_configuration_reference == nil
             xcconfig_path = config.base_configuration_reference.real_path
             File.open(xcconfig_path, 'a+') do |file|
                 file.puts "#include \"#{File.realpath(File.join(framework_dir, 'Generated.xcconfig'))}\""