With the following report:
https://gist.github.com/roidelapluie/5049d83253b382406fd7

I get

Report for fna060.ant.inuits.lab in environment example at 2016-03-14 11:36:36 +0100

             Report File: last_run_report.yaml
             Report Kind: apply
          Puppet Version: 4.3.2
           Report Format: 4
   Configuration Version: 
                    UUID: 5432ba46-f86c-4fbe-9282-71ad86ce1943
               Log Lines: 7 (show with --log)

Report Metrics:

report_print.rb:65:in `print_report_metrics': undefined method `+' for nil:NilClass (NoMethodError)
        from report_print.rb:198:in `<main>'

root # ruby -v
ruby 1.8.7 (2013-06-27 patchlevel 374) [x86_64-linux]
root # puppet -V
3.7.4
root #./report_print.rb --nodelist
./report_print.rb:76: syntax error, unexpected ')'

I got several syntax errors:

root@puppet1:/usr/bin# ruby -v
ruby 1.9.3p194 (2012-04-20 revision 35410) [i486-linux]

root@puppet1:/usr/bin# puppet --version
3.6.2

root@puppet1:/usr/bin# ruby -c report_print.rb
report_print.rb:40: syntax error, unexpected tSTRING_BEG, expecting keyword_do or '{' or '('
...= {:red => " return "%s%s%s%s" % [colors.fetch(code, ""), m...
... ^
report_print.rb:46: syntax error, unexpected tCONSTANT, expecting keyword_end
puts color(:bold, "Report for %s in environment %s at ...
^
report_print.rb:46: syntax error, unexpected tIDENTIFIER, expecting tCOLON2 or '[' or '.'
..., "Report for %s in environment %s at %s" % [color(:underlin...
... ^
report_print.rb:46: syntax error, unexpected tIDENTIFIER, expecting keyword_do or '{' or '('
...ort for %s in environment %s at %s" % [color(:underline, rep...
... ^
report_print.rb:48: syntax error, unexpected tCONSTANT, expecting keyword_end
puts " Report File: %s" % @options[:report]
^
report_print.rb:49: syntax error, unexpected tCONSTANT, expecting keyword_end
puts " Report Kind: %s" % report.kind
^
report_print.rb:50: syntax error, unexpected tCONSTANT, expecting keyword_end
puts " Puppet Version: %s" % report.puppet_version
^
report_print.rb:51: syntax error, unexpected tCONSTANT, expecting keyword_end
puts " Report Format: %s" % report.report_format
^
report_print.rb:52: syntax error, unexpected tCONSTANT, expecting keyword_end
puts " Configuration Version: %s" % report.configuration_version
^
report_print.rb:53: syntax error, unexpected tCONSTANT, expecting keyword_end
... puts " UUID: %s" % report.transaction_uu...
... ^
report_print.rb:54: syntax error, unexpected tCONSTANT, expecting keyword_end
puts " Log Lines: %s %s" % [report.logs...
^
report_print.rb:65: syntax error, unexpected keyword_do_block, expecting keyword_end
report.metrics.sort_by{|i, m| m.label}.each do |i, metric|
^
report_print.rb:65: syntax error, unexpected '|', expecting '='
report_print.rb:68: syntax error, unexpected keyword_do_block, expecting keyword_end
metric.values.sort_by{|i, m, v| v}.reverse.each do |i, m, v|
^
report_print.rb:68: syntax error, unexpected '|', expecting '='
report_print.rb:73: syntax error, unexpected keyword_end, expecting $end