Fix Ruby script bug

Hello! I'm using a script called pdf-extract ([login to view URL]) to extract xml from pdf files. However, the script is throwing an error on some pdfs, for example on the pdf attached. The error (see below) seems quite straight forward to fix, but I don't have any experience with Ruby so that's why I need some help. See the stack trace below: pdf-extract --trace extract --headers --footers --references --no-lines --regions --set char_slop:0.4 [login to view URL] > [login to view URL] /var/lib/gems/2.1.0/gems/pdf-extract-0.1.1/lib/pdf/extract/[login to view URL]:inblock (3 levels) in invoke_calls': zones is missing a dependency on left_margins (RuntimeError) from /var/lib/gems/2.1.0/gems/pdf-extract-0.1.1/lib/pdf/extract/[login to view URL]:in each' from /var/lib/gems/2.1.0/gems/pdf-extract-0.1.1/lib/pdf/extract/[login to view URL]:inblock (2 levels) in invoke_calls' from /var/lib/gems/2.1.0/gems/pdf-extract-0.1.1/lib/pdf/extract/[login to view URL]:in each_pair' from /var/lib/gems/2.1.0/gems/pdf-extract-0.1.1/lib/pdf/extract/[login to view URL]:inblock in invoke_calls' from /var/lib/gems/2.1.0/gems/pdf-extract-0.1.1/lib/pdf/extract/[login to view URL]:in each_pair' from /var/lib/gems/2.1.0/gems/pdf-extract-0.1.1/lib/pdf/extract/[login to view URL]:ininvoke_calls' from /var/lib/gems/2.1.0/gems/pdf-extract-0.1.1/lib/pdf/[login to view URL]:in block in parse' from /var/lib/gems/2.1.0/gems/pdf-extract-0.1.1/lib/pdf/[login to view URL]:ineach' from /var/lib/gems/2.1.0/gems/pdf-extract-0.1.1/lib/pdf/[login to view URL]:in parse' from /var/lib/gems/2.1.0/gems/pdf-extract-0.1.1/lib/pdf/[login to view URL]:inview' from /var/lib/gems/2.1.0/gems/pdf-extract-0.1.1/bin/pdf-extract:121:in block (4 levels) in <top (required)>' from /var/lib/gems/2.1.0/gems/pdf-extract-0.1.1/bin/pdf-extract:118:ineach' from /var/lib/gems/2.1.0/gems/pdf-extract-0.1.1/bin/pdf-extract:118:in block (3 levels) in <top (required)>' from /var/lib/gems/2.1.0/gems/commander-4.4.3/lib/commander/[login to view URL]:incall' from /var/lib/gems/2.1.0/gems/commander-4.4.3/lib/commander/[login to view URL]:in call' from /var/lib/gems/2.1.0/gems/commander-4.4.3/lib/commander/[login to view URL]:inrun' from /var/lib/gems/2.1.0/gems/commander-4.4.3/lib/commander/[login to view URL]:in run_active_command' from /var/lib/gems/2.1.0/gems/commander-4.4.3/lib/commander/[login to view URL]:inrun!' from /var/lib/gems/2.1.0/gems/commander-4.4.3/lib/commander/[login to view URL]:in run!' from /var/lib/gems/2.1.0/gems/commander-4.4.3/lib/commander/[login to view URL]:inblock in <top (required)>'`