Foo.js

import React, { Component } from 'react'
import PropTypes from 'prop-types'
import Baz from 'baz'

class Foo extends Component {
  static propTypes = {
    list: PropTypes.array,
  }

  static defaultProps = {
    list: '',
  }

  items = (list) => {
    const filteredList = list
      .filter(i => i !== null)
      .map(item => ({ bar: item.baz }))

    return filteredList.map((item, index) => (
      <Baz 
        key={index} 
        bar={item.bar}
        something={item.bar}
      />
    ))
  }

  render() {
    const { list } = this.props

    return (
      <div>
        {list && (
          <div>
            {`Count is ${this.props.count} for items: `} {this.items(list)}
          </div> 
        )}
        {!list && (
          {`Count is ${this.props.count} for items: `} n/a
        )}
      </div>
    )
  }
}