Gem::Commands::BuildCommand#error_message

# File tmp/rubies/ruby-3.3.0/lib/rubygems/commands/build_command.rb, line 125
def error_message
  if gem_name
    "Couldn't find a gemspec file matching '#{gem_name}' in #{Dir.pwd}"
  else
    "Couldn't find a gemspec file in #{Dir.pwd}"
  end
end