d12frosted/homebrew-emacs-plus · error · ConfigurationError

Invalid '#{key}' in #{path} Expected: string (icon name) or

Error message

Invalid '#{key}' in #{path}
Expected: string (icon name) or object with 'url' and 'sha256'
Got: #{icon.inspect} (#{icon.class})

What it means

The icon entry (top-level `icon`, or an `icon.<version>` value inside a version map) has a type the validator does not accept: the `else` branch of validate_icon_spec! (Library/BuildConfig.rb:242-247) allows only String (registry icon name), nil, or Hash ({url, sha256}). Everything else - Array, Integer, Float, TrueClass/FalseClass - is rejected with the value's inspect output and its class in the message.

Source

Thrown at Library/BuildConfig.rb:243

      else
        validate_icon_spec!(icon, path)
      end
    end

    def validate_icon_spec!(icon, path, key: "icon")
      case icon
      when String, nil
        # Valid: icon name from registry or no icon
        return
      when Hash
        unless icon["url"] && icon["sha256"]
          raise ConfigurationError,
            "Invalid '#{key}' configuration in #{path}\n" \
            "When specifying an external icon, both 'url' and 'sha256' are required.\n" \
            "Got: #{icon.inspect}"
        end
      else
        raise ConfigurationError,
          "Invalid '#{key}' in #{path}\n" \
          "Expected: string (icon name) or object with 'url' and 'sha256'\n" \
          "Got: #{icon.inspect} (#{icon.class})"
      end
    end

    # Validate that all keys of a version map are major versions or "default"
    def validate_version_map_keys!(map, key, path)
      bad = map.keys.reject { |k| k.to_s == "default" || k.to_s.match?(VERSION_KEY) }
      return if bad.empty?

      raise ConfigurationError,
        "Invalid '#{key}' version map in #{path}\n" \
        "Version keys must be major Emacs versions (e.g. \"30\") or 'default'.\n" \
        "Got key(s): #{bad.map(&:inspect).join(', ')}"
    end

    def validate_inject_path!(value, path)

View on GitHub (pinned to 01c47fe98f)

Solutions

1. Use one of the two accepted shapes: a single string icon name, or an external spec hash with url and sha256.
2. Remove list/bracket syntax - arrays are never valid for icon.
3. Quote values YAML would otherwise type as numbers or booleans ("30", "true", "no") so they stay strings.
4. If the entry was a mistake, delete the icon key - it is optional.

Example fix

# before - array of names
icon: [Spacemacs, Emacs-Icon]

# after - one string name
icon: Spacemacs

def icon_ref?(v)
  v.is_a?(String) || v.nil? || v.is_a?(Hash)
end
# use on config_hash["icon"], and on each per-version value when icon is a version map

begin
  BuildConfig.load_config
rescue BuildConfig::ConfigurationError => e
  if e.message.include?("Expected: string (icon name)")
    abort "icon must be a name string or {url, sha256} - see the Got: line in the error"
  end
  raise
end

When it happens

Trigger: `icon: [Spacemacs, Emacs-Icon]` (YAML list), `icon: 42`, `icon: 3.14`, `icon: true` / `icon: yes`; or the same wrong types as values inside a version map, e.g. `icon: {"30": [a]}`.

Common situations: Trying to list several candidate icons; unquoted values that YAML implicitly types as numbers or booleans (a name like `30` or `no` becomes Integer/FalseClass unless quoted); copying JSON-ish config where brackets were fine.

Related errors

• Invalid build.yml at #{path} Expected a YAML mapping (key: v
• Invalid 'icon.#{ver}' in #{path} Version maps cannot be nest
• Invalid '#{key}' configuration in #{path} When specifying an
• YAML syntax error in #{path} #{e.message} Tip: Validate you
• Unknown configuration key(s) in #{path}: #{unknown_keys.join

AI-assisted analysis of d12frosted/homebrew-emacs-plus@01c47fe98f (2026-08-23). Data as JSON: /api/errors/582d819257142cc7. Report an issue: GitHub.