```ruby
require "fit-commit/runner"

module FitCommit
  def self.run
    exit_code = runner.run
    exit(exit_code)
  end

  private

  def self.runner
    FitCommit::Runner.new(message_path, branch_name)
  end

  def self.message_path
    ENV.fetch("COMMIT_MESSAGE_PATH")
  end

  def self.branch_name
    ENV.fetch("GIT_BRANCH_NAME")
  end
end
```

Add error message for backwards compatibility
user
```ruby
require "fit-commit/runner"

module FitCommit
  def self.run
    exit_code = runner.run
    exit(exit_code)
  end

  private

  def self.runner
    FitCommit::Runner.new(message_path, branch_name)
  end

  def self.message_path
    ENV.fetch("COMMIT_MESSAGE_PATH")
  end

  def self.branch_name
    ENV["GIT_BRANCH_NAME"] ||
      fail("Git branch not found. You might need to re-run `fit-commit install`")
  end
end
```
assistant