add key to selectors

src/components/Selector.js

@@ -2,7 +2,11 @@ import React from 'react';
 import PropTypes from 'prop-types';
 
 export default function Selector(props) {
-  const lists = props.lists.map(list => <option value={list.id}>{list.name}</option>);
+  const lists = props.lists.map(list => (
+    <option key={list.id} value={list.id}>
+      {list.name}
+    </option>
+  ));
   return (
     <div>
       <select defaultValue={props.list} onChange={e => props.onChange(e.target.value)}>
@@ -14,7 +18,7 @@ export default function Selector(props) {
 
 Selector.propTypes = {
   lists: PropTypes.arrayOf(PropTypes.shape({
-    id: PropTypes.number.isRequired,
+    id: PropTypes.string.isRequired,
     slug: PropTypes.string.isRequired,
   })).isRequired,
   list: PropTypes.string.isRequired,