enforce better variable name than e for exceptions via rubocop

[evgeni]

          Looks like that cop is designed to help enforce a standard across your project, and defaults to `e`. So we could set it to `error` in the Rubocop config (https://www.rubydoc.info/gems/rubocop/0.75.0/RuboCop/Cop/Naming/RescuedExceptionsVariableName)

Granted, looks like we do not see this error currently because we are using => e everywhere already. Ok - stick with our current standard - file me a Github issue?

Originally posted by @ehelms in #856 (comment)