Rails won't boot after better error update

Hi @haileys ,

I have a rails app that use `better_errors`.

After an update of this library, I come with a `LoadError: cannot load such file -- sassc`.

Digging into the source code, I have spotted that `sassc` is a development depency
https://github.com/BetterErrors/better_errors/blob/55ce4f69be35f652e4b967ad2f720ec4d6c5c72f/better_errors.gemspec#L28

However, it is load in https://github.com/BetterErrors/better_errors/blob/55ce4f69be35f652e4b967ad2f720ec4d6c5c72f/lib/better_errors/error_page_style.rb#L1

Should not it be a runtime dependency ?

Regards,

Read the referenced better_errors.gemspec dependency entry and lib/better_errors/error_page_style.rb first, then reproduce the LoadError in a Rails app using better_errors. Done means the dependency declaration matches the library's runtime loading requirements and the app boots without the reported sassc error.

Written by the indexing model from the issue text.