Regression: puppet help errors out if any application raises while generating help

PUP-3521 (commit eccd3b modified puppet to not swallow errors silently, but it causes a regression because the result variable is not in scope. To reproduce, modify an app in lib/puppet/application/*.rb to raise an ArgumentError in its help method, then run:

bundle exec puppet help

Error: undefined local variable or method `result' for #<Puppet::Interface:0x007fab1b563218>

...

The problem line is:

    rescue StandardError

      result << [ "! #{appname}", "! Subcommand unavailable due to error. Check error logs." ]

    end

Although the reproduction steps are contrived, I ran into this problem when I had an application in a module and the application called Puppet.settings.initialize_settings twice, which causes puppet to raise an exception.