Info.jsx

const Info = props => {
  const missed = [...new Set(props.word.split(""))].filter(
    letter => !props.usedLetters.includes(letter)
  );

  if (!props.health) {
      return null;
  }

  return (
    <div>
        <div id="message">YOU MISSED:</div>
        <div id="missed" style={{ color: "#4C71FA" }}>
        {missed.join(", ")}
        </div>
        ({props.word})
    </div>
  );
}