During January 2025, Sanjo Oh worked on the ruby/ruby repository, focusing on improving error reporting for undefined methods in the rb_alias function. By modifying the C implementation to pass target_klass to rb_print_undef, Sanjo enhanced the clarity and context of error messages, particularly in complex aliasing and zsuper scenarios. This update was reinforced with a new regression test in Ruby, ensuring the improved messaging was robust and reliable. Sanjo’s work leveraged expertise in C programming, Ruby internals, and error handling, resulting in clearer diagnostics and reduced debugging time for developers working with method aliasing in Ruby’s core codebase.