segmentation error on Ruby 2.1.9

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Just started seeing these periodically since updating my Ruby. Any ideas to a likely cause?

/Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/rack-1.6.4/lib/rack/lint.rb:274: [BUG] Segmentation fault at 0x00000000000100
ruby 2.1.9p490 (2016-03-30 revision 54437) [x86_64-darwin14.0]

-- Crash Report log information --------------------------------------------
   See Crash Report log file under the one of following:
     * ~/Library/Logs/CrashReporter
     * /Library/Logs/CrashReporter
     * ~/Library/Logs/DiagnosticReports
     * /Library/Logs/DiagnosticReports
   for more details.

-- Control frame information -----------------------------------------------
c:0031 p:---- s:0152 e:000151 CFUNC  :inspect
c:0030 p:0031 s:0149 e:000144 BLOCK  /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/rack-1.6.4/lib/rack/lint.rb:274 [FINISH]
c:0029 p:---- s:0141 e:000140 CFUNC  :each
c:0028 p:0301 s:0138 E:0012c0 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/rack-1.6.4/lib/rack/lint.rb:272
c:0027 p:0017 s:0130 E:002510 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/rack-1.6.4/lib/rack/lint.rb:43
c:0026 p:0014 s:0124 e:000123 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/rack-1.6.4/lib/rack/lint.rb:37
c:0025 p:0011 s:0120 e:000119 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/rack-1.6.4/lib/rack/showexceptions.rb:24
c:0024 p:0011 s:0112 e:000111 METHOD /Users/jamestindall/Documents/doc_baton/BatonSite/dist/server/helpers/disable_rack_logger.rb:6
c:0023 p:0011 s:0108 e:000107 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/rack-1.6.4/lib/rack/chunked.rb:54
c:0022 p:0011 s:0101 e:000100 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/rack-1.6.4/lib/rack/content_length.rb:15
c:0021 p:0014 s:0092 e:000091 BLOCK  /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/thin-1.7.0/lib/thin/connection.rb:86 [FINISH]
c:0020 p:---- s:0090 e:000089 CFUNC  :catch
c:0019 p:0091 s:0086 e:000085 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/thin-1.7.0/lib/thin/connection.rb:84
c:0018 p:0020 s:0080 e:000079 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/sinatra-websocket-0.3.1/lib/sinatra-websocket/ext/thin/connection.rb:26
c:0017 p:0048 s:0077 e:000075 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/thin-1.7.0/lib/thin/connection.rb:53
c:0016 p:0031 s:0073 e:000072 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/thin-1.7.0/lib/thin/connection.rb:39
c:0015 p:0027 s:0068 e:000067 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/sinatra-websocket-0.3.1/lib/sinatra-websocket/ext/thin/connection.rb:40
c:0014 p:0041 s:0064 e:000063 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/sinatra-websocket-0.3.1/lib/sinatra-websocket/ext/thin/connection.rb:65 [FINISH]
c:0013 p:---- s:0059 e:000058 CFUNC  :run_machine
c:0012 p:0307 s:0056 e:000055 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/eventmachine-1.2.0.1/lib/eventmachine.rb:194
c:0011 p:0057 s:0049 E:0011b0 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/thin-1.7.0/lib/thin/backends/base.rb:73
c:0010 p:0111 s:0045 E:0011c8 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/thin-1.7.0/lib/thin/server.rb:162
c:0009 p:0175 s:0042 e:000041 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/rack-1.6.4/lib/rack/handler/thin.rb:19
c:0008 p:0194 s:0031 E:0014c0 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/rack-1.6.4/lib/rack/server.rb:286
c:0007 p:0014 s:0025 e:000024 METHOD /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/rack-1.6.4/lib/rack/server.rb:147
c:0006 p:0021 s:0021 e:000020 TOP    /Users/jamestindall/.rvm/gems/ruby-2.1.9/gems/rack-1.6.4/bin/rackup:4 [FINISH]
c:0005 p:---- s:0019 e:000018 CFUNC  :load
c:0004 p:0135 s:0015 E:001928 EVAL   /Users/jamestindall/.rvm/gems/ruby-2.1.9/bin/rackup:23 [FINISH]
c:0003 p:---- s:0011 e:000010 CFUNC  :eval
c:0002 p:0118 s:0005 E:001000 EVAL   /Users/jamestindall/.rvm/gems/ruby-2.1.9/bin/ruby_executable_hooks:15 [FINISH]
c:0001 p:0000 s:0002 E:001128 TOP    [FINISH]