• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew lgtm (style, typechecking and tests) with your changes locally?

Ignoring errors disables proper exception handling which leads to unexpected code paths that can cause Sorbet errors rather than FormulaUnreadableError. Sorbet errors then cascade up and cause brew to not run properly.

Need someone to check if this was intentionally set to ignore_errors: true

At least helps with brew doctor part of

• brew upgrade and brew doctor failing with HOMEBREW_USE_INTERNAL_API set - Error: Passed nil into T.must #21055

e.g. reproduced with my existing install of tmux which was installed before we dropped Sierra from Formula

❯ rg on_system $(brew --prefix tmux)/.brew/tmux.rb
30:  on_system :linux, macos: :sierra_or_newer do

before

❯ HOMEBREW_USE_INTERNAL_API=1 brew doctor
Error: Passed `nil` into T.must
Warning: Removed Sorbet lines from backtrace!
Rerun with `--verbose` to see the original backtrace
/opt/homebrew/Library/Homebrew/ignorable.rb:30:in 'block in Object#raise'
/opt/homebrew/Library/Homebrew/ignorable.rb:29:in 'Kernel#callcc'
/opt/homebrew/Library/Homebrew/ignorable.rb:29:in 'Object#raise'
/opt/homebrew/Library/Homebrew/macos_version.rb:58:in 'MacOSVersion#initialize'

after

❯ HOMEBREW_USE_INTERNAL_API=1 brew doctor
Your system is ready to brew.