Fix RuboCop redundant return violations

Remove redundant return statements from error handling methods as flagged by
Style/RedundantReturn. These returns are not needed since the methods end
with the conditional raise statement.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: justin808

lib/generators/react_on_rails/install_generator.rb

@@ -240,8 +240,6 @@ def handle_shakapacker_gemfile_error
         MSG
         GeneratorMessages.add_error(error)
         raise Thor::Error, error unless options.ignore_warnings?
-
-        return
       end
 
       def handle_shakapacker_install_error
@@ -264,8 +262,6 @@ def handle_shakapacker_install_error
         MSG
         GeneratorMessages.add_error(error)
         raise Thor::Error, error unless options.ignore_warnings?
-
-        return
       end
 
       def missing_package_manager?