arrange error message of 'brew edit --cask'

[hyuraku]

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arrange the error message of brew edit --cask like one of brew edit --formula

• before PR

$ brew edit --cask atomm
Usage: brew edit [options] [formula|cask ...]

Open a formula or cask in the editor set by EDITOR or HOMEBREW_EDITOR,
or open the Homebrew repository for editing if no formula is provided.

      --formula, --formulae        Treat all named arguments as formulae.
      --cask, --casks              Treat all named arguments as casks.
      --print-path                 Print the file path to be edited, without
                                   opening an editor.
  -d, --debug                      Display any debugging information.
  -q, --quiet                      Make some output more quiet.
  -v, --verbose                    Make some output more verbose.
  -h, --help                       Show this message.

Error: Invalid usage: /opt/homebrew/Library/Taps/homebrew/homebrew-cask/Casks/atomm.rb doesn't exist on disk. Run brew create --set-name atomm.rb $URL to create a new formula!

• after PR

$ brew edit --cask atomm
Usage: brew edit [options] [formula|cask ...]

--< omitted >--

Error: Invalid usage: atomm doesn't exist on disk. Run brew create --cask --set-name atomm $URL to create a new cask!

[MikeMcQuaid]

Thanks again @hyuraku!