Upon investigation this error raised by the awesome_print library points to a problem with the value in the ENV['HOME'] environment variable. It is probably not set.
This will only occur if ENV['HOME'] is not set AND the rubydebug codec is used. The awesome_print library maintainers have fixed this in master but not released the fix yet. I have asked them to do this.
That said, even if it was fixed, you might still have problems with Logstash or some plugins as the POSIX specification requires that it is set.