code: function helper(context, helpers, helperName, args) {
    if (typeof helpers[helperName] !== 'function') {
      return '';
    }
    try {
      const out = helpers[helperName].apply(context, args);
      return out || '';
    } catch (e) {
      return '';
    }
  }
docs: Execute a helper
  @param {object} context - Base data object
  @param {object} helpers - Map of helper functions
  @param {string} helperName - Name of helper to execute
  @param {any[]} args - Array of arguments
  @returns {string}