Verification

• This issue's title and/or description do not reference a single formula e.g. brew install wget. If they do, open an issue at https://github.com/Homebrew/homebrew-core/issues/new/choose instead.

Provide a detailed description of the proposed feature

There is no information about a error in executing brew install /path/to/formula.rb except "There is no formula in /path/to/formula". It will be useful to add info about HOMEBREW_DEVELOPER environment variable in case of guessing path in user's input.

What is the motivation for the feature?

I spent 2 hours to make command working which I debug yesterday. I couldn't find any info except brew version mismatch between my macbook and the other one.

How will the feature be relevant to at least 90% of Homebrew users?

90% of Homebrew users don't make formulas so...

What alternatives to the feature have been considered?

More documentation I guess.