Developer UX: better error for misspelled/missing attribute

[monkbroc]

If a field in COLLECTION_ATTRIBUTES has no key in ATTRIBUTE_TYPES either because I misspelled it or I forget to add it to ATTRIBUTE_TYPES I will get a undefined method new for nil:NilClass in Page::Base

It would be nicer to see a custom exception Attribute xyz not found in dashboard AbcDashboard

This has already happened multiple times on my first day of using Administrate so I think this is worthwhile to fix.

[c-lliope]

👍 good call, I think this would be super useful.

[5minpause]

@Graysonwright @monkbroc I gave a possible implementation a try.
https://github.com/ikuseiGmbH/administrate/commit/62570b673bd43964db8d9dfc09b6fddb1ec7b8be

Could you provide feedback, please? I wasn't sure how to add a test for that. Any hints would be appreciated.
Also I don't know how Thoughtbot deals with HEREDOCS? Do you use indentation?

[monkbroc]

Thanks @5minpause. I commented on your commit.

[c-lliope]

@5minpause can you open a PR for that commit, so we can leave comments on it more effectively?

For HEREDOCs, I usually go with this:

  string = <<-SOMETHING.strip_heredoc
    If you use `<<-` instead of `<<`,
    it lets you indent the closing tag.
    The `strip_heredoc` removes leading indentation
    for the heredoc string.
  SOMETHING

Sources:
http://rubyquicktips.com/post/4438542511/heredoc-and-indent
http://apidock.com/rails/String/strip_heredoc