createQuery on empty table throws an error

[roelvan]

Steps to reproduce

Changing the knex query (via createQuery()) in a before hook returns an error when there are 0 rows in my postgres DB:

TypeError: Cannot read property 'total' of undefined
    at countQuery.then.count (/path/to/node_modules/feathers-knex/lib/index.js:184:48)

As soon as there are rows, everything works fine.

My before hook that does a count / join:

const { mapKeys } = require('lodash');

module.exports = (options = {}) => { // eslint-disable-line no-unused-vars
  return async context => {
    // PREVENT: "column reference "[column name]" is ambiguous"
    const sort = mapKeys(context.params.query.$sort, (order, field) => `plannings.${field}`);
    context.params.query.$sort = sort;
    
    const query = context.service.createQuery({ query: context.params.query });
    query
      .count('plannings.id as planninRuleCount')
      .leftJoin('planningRules as plr', 'plr.planningId', 'plannings.id')
      .groupBy('plannings.id');
    
    if (context.id) // Scope the query if it's a single GET call
      query.where('plannings.id', context.id);
    
    context.params.knex = query;
    return context;
  };
};