Warning from pry-stack_explorer when using with Pry

[RobinDaugherty]

When Pry is enabled, the following warning is output when the console is used:

when_started hook failed: NoMethodError: undefined method `last' for nil:NilClass
/usr/local/var/rbenv/versions/2.4.0/lib/ruby/gems/2.4.0/gems/pry-stack_explorer-0.4.9.2/lib/pry-stack_explorer/when_started_hook.rb:50:in `remove_internal_frames'
(see _pry_.hooks.errors to debug)

This is not a fatal error, so Better Errors is still working, and the result is displayed following this warning message.