Receiving conversion TypeError when trying to bump version

[tmr08c]

Sample backtrace when trying to bump a version:

> versionify bump patch
/Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/git_version_bumper-1.0.2/lib/git_version_bumper/version_bumper/tag.rb:11:in `Integer': invalid value for Integer(): "" (ArgumentError)
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/git_version_bumper-1.0.2/lib/git_version_bumper/version_bumper/tag.rb:11:in `initialize'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/git_version_bumper-1.0.2/lib/git_version_bumper/version_bumper/tag.rb:30:in `new'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/git_version_bumper-1.0.2/lib/git_version_bumper/version_bumper/tag.rb:30:in `from_name'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/git_version_bumper-1.0.2/lib/git_version_bumper/version_bumper/tag.rb:21:in `block in current'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/git_version_bumper-1.0.2/lib/git_version_bumper/version_bumper/tag.rb:21:in `map'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/git_version_bumper-1.0.2/lib/git_version_bumper/version_bumper/tag.rb:21:in `current'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/git_version_bumper-1.0.2/lib/git_version_bumper/version_bumper/bumper.rb:37:in `current_tag'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/git_version_bumper-1.0.2/lib/git_version_bumper/version_bumper/bumper.rb:41:in `current_major_version'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/git_version_bumper-1.0.2/lib/git_version_bumper/version_bumper/patch_version_bumper.rb:11:in `tag'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/git_version_bumper-1.0.2/lib/git_version_bumper/version_bumper/bumper.rb:21:in `bump'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/git_version_bumper-1.0.2/lib/git_version_bumper/cli.rb:28:in `bump'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/thor-0.20.0/lib/thor/command.rb:27:in `run'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/thor-0.20.0/lib/thor/invocation.rb:126:in `invoke_command'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/thor-0.20.0/lib/thor.rb:387:in `dispatch'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/thor-0.20.0/lib/thor/base.rb:466:in `start'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/gems/git_version_bumper-1.0.2/bin/versionify:7:in `<top (required)>'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/bin/versionify:23:in `load'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/bin/versionify:23:in `<main>'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/bin/ruby_executable_hooks:15:in `eval'
        from /Users/troyrosenberg/.rvm/gems/ruby-2.1.9@dash/bin/ruby_executable_hooks:15:in `<main>'