Error:

  [2014-03-10 15:38:12] ERROR TypeError: nil can't be coerced into Fixnum
	/usr/local/Cellar/ruby/2.1.1/lib/ruby/gems/2.1.0/gems/server_metrics-1.2.0/lib/server_metrics/collectors/memory.rb:81:in `+'

Here's the output:

  [~] top -l1 -n0 -u
  Processes: 268 total, 3 running, 5 stuck, 260 sleeping, 2070 threads
  2014/03/10 15:36:26
  Load Avg: 1.92, 2.05, 2.08
  CPU usage: 4.46% user, 12.50% sys, 83.3% idle
  SharedLibs: 60M resident, 0B data, 4156K linkedit.
  MemRegions: 73352 total, 3529M resident, 83M private, 892M shared.
  PhysMem: 6726M used (1812M wired), 199M unused.
  VM: 570G vsize, 1312M framework vsize, 1570984(0) swapins, 1861805(0) swapouts.
  Networks: packets: 2441317/1583M in, 1428870/324M out.
  Disks: 3446592/122G read, 1578215/101G written.

Processes: 180 total, 2 running, 7 stuck, 171 sleeping, 965 threads 2014/03/10 16:24:55 Load Avg: 1.28, 1.13, 1.06 CPU usage: 8.0% user, 20.0% sys, 72.0% idle SharedLibs: 12M resident, 12M data, 0B linkedit. MemRegions: 35120 total, 1588M resident, 121M private, 700M shared. PhysMem: 5020M used (853M wired), 2884M unused. VM: 401G vsize, 1065M framework vsize, 311(0) swapins, 1527(0) swapouts. Networks: packets: 14047540/18G in, 8183740/2177M out. Disks: 386988/26G read, 413161/25G written.