Support old versions of React (rjsf-team#312)

See https://github.com/facebook/react/blob/master/CHANGELOG.md#1500-april-7-2016

Author: rom10

src/components/fields/ArrayField.js

@@ -20,15 +20,17 @@ import CheckboxesWidget from "./../widgets/CheckboxesWidget";
 
 function ArrayFieldTitle({TitleField, idSchema, title, required}) {
  if (!title) {
- return null;
+ // See #312: Ensure compatibility with old versions of React.
+ return <div />;
  }
  const id = `${idSchema.$id}__title`;
  return <TitleField id={id} title={title} required={required} />;
 }
 
 function ArrayFieldDescription({DescriptionField, idSchema, description}) {
  if (!description) {
- return null;
+ // See #312: Ensure compatibility with old versions of React.
+ return <div />;
  }
  const id = `${idSchema.$id}__description`;
  return <DescriptionField id={id} description={description} />;

src/components/fields/DescriptionField.js

@@ -3,7 +3,8 @@ import React, {PropTypes} from "react";
 function DescriptionField(props) {
  const {id, description} = props;
  if (!description) {
- return null;
+ // See #312: Ensure compatibility with old versions of React.
+ return <div />;
  }
  if (typeof description === "string") {
  return <p id={id} className="field-description">{description}</p>;

src/components/fields/SchemaField.js

@@ -38,7 +38,8 @@ function getFieldComponent(schema, uiSchema, fields) {
 function Label(props) {
  const {label, required, id} = props;
  if (!label) {
- return null;
+ // See #312: Ensure compatibility with old versions of React.
+ return <div />;
  }
  return (
  <label className="control-label" htmlFor={id}>
@@ -50,7 +51,8 @@ function Label(props) {
 function Help(props) {
  const {help} = props;
  if (!help) {
- return null;
+ // See #312: Ensure compatibility with old versions of React.
+ return <div />;
  }
  if (typeof help === "string") {
  return <p className="help-block">{help}</p>;
@@ -61,7 +63,7 @@ function Help(props) {
 function ErrorList(props) {
  const {errors = []} = props;
  if (errors.length === 0) {
- return null;
+ return <div />;
  }
  return (
  <div>
@@ -137,6 +139,7 @@ function SchemaField(props) {
  const autofocus = Boolean(props.autofocus || uiSchema["ui:autofocus"]);
 
  if (Object.keys(schema).length === 0) {
+ // See #312: Ensure compatibility with old versions of React.
  return <div />;
  }