This changes the behavior of Kernel#puts in a subtle, problematic way

[myronmarston]

Kernel#puts is documented as returning nil, and that is how it normally behaves:

$ irb
2.7.5 :001 > puts "abc"
abc
 => nil

However, in this project you monkey patch Kernel#puts. A (presumably unintended) side effect of that monkey patch is that it changes the return value to an Integer (since that's what AwsLambdaRuntimeInterfaceClient::TelemetryLoggingHelper.telemetry_log_sink.write(msg) returns, and that's the last line of your puts redefinition).

To make your monkey patch safer, it should still return nil from puts (e.g. by adding a last line to the method of nil).

Concretely, this led to an exception I got from code that assumed that puts does indeed return nil but when run in a lambda that wasn't true.

[mullermp]

This is handled now in the latest release:

aws-lambda-ruby-runtime-interface-client/lib/aws_lambda_ric.rb

Line 178 in 54e07e1

return nil