Apply suggestions from code review

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

Author: justin808

lib/react_on_rails/configuration.rb

@@ -333,7 +333,7 @@ def raise_missing_components_subdirectory
     end
 
     def compile_command_conflict_message
-      packer_name = ReactOnRails::PackerUtils.packer_type&.upcase_first
+      packer_name = ReactOnRails::PackerUtils.packer_type.upcase_first
       packer_type = ReactOnRails::PackerUtils.packer_type
       <<~MSG