GoogleChrome/lighthouse · error · Error

${pluginName} has a group not defined as an object.

Error message

${pluginName} has a group not defined as an object.

What it means

Thrown by ConfigPlugin._parseGroups while iterating Object.entries(groups). Each value in the groups map must itself be a plain object (isObjectOfUnknownProperties). If any group entry is null, an array, a string, or a number, this error fires.

Source

Thrown at core/config/config-plugin.js:199

   * @param {string} pluginName
   * @return {Record<string, LH.Config.GroupJson>|undefined}
   */
  static _parseGroups(groupsJson, pluginName) {
    if (groupsJson === undefined) {
      return undefined;
    }

    if (!isObjectOfUnknownProperties(groupsJson)) {
      throw new Error(`${pluginName} groups json is not defined as an object.`);
    }

    const groups = Object.entries(groupsJson);

    /** @type {Record<string, LH.Config.GroupJson>} */
    const parsedGroupsJson = {};
    groups.forEach(([groupId, groupJson]) => {
      if (!isObjectOfUnknownProperties(groupJson)) {
        throw new Error(`${pluginName} has a group not defined as an object.`);
      }
      const {title, description, ...invalidRest} = groupJson;
      assertNoExcessProperties(invalidRest, pluginName, 'group');

      if (!i18n.isStringOrIcuMessage(title)) {
        throw new Error(`${pluginName} has an invalid group title.`);
      }
      if (!i18n.isStringOrIcuMessage(description) && description !== undefined) {
        throw new Error(`${pluginName} has an invalid group description.`);
      }
      parsedGroupsJson[`${pluginName}-${groupId}`] = {
        title,
        description,
      };
    });
    return parsedGroupsJson;
  }

View on GitHub (pinned to 9515cd4e58)

Solutions

  1. Make every group value an object with at least a title: groups: {groupA: {title:'Group A'}}.
  2. Delete the malformed group key if it is not needed.

Example fix

// before
groups: {performance: 'Performance metrics'}
// after
groups: {performance: {title: 'Performance metrics', description: 'Speed metrics'}}
Defensive patterns

Strategy: validation

Validate before calling

function isPlainObject(v) { return typeof v === 'object' && v !== null && !Array.isArray(v); }
for (const [id, g] of Object.entries(plugin.groups || {})) {
  if (!isPlainObject(g)) throw new TypeError(`group '${id}' must be an object`);
}

Type guard

function everyGroupIsObject(groups) {
  return Object.values(groups).every(g => typeof g === 'object' && g !== null && !Array.isArray(g));
}

Try / catch

try { await ConfigPlugin.parsePlugin(plugin, name); }
catch (e) { if (/group not defined as an object/.test(e.message)) console.error('Each group must be {title,...}'); throw e; }

Prevention

When it happens

Trigger: groups: {groupA: 'My Group'} or groups: {groupA: null} or groups: {groupA: [{...}]}. The per-group value is not a plain object, so config-plugin.js:199 throws.

Common situations: Writing a group as a bare title string instead of {title:'...'}. Copy-paste leaving an empty placeholder. YAML producing null for an unset group.

Related errors

AI-assisted analysis of GoogleChrome/lighthouse@9515cd4e58 (2026-08-13). Data as JSON: /api/errors/64341faf84ae8636. Report an issue: GitHub.