Formik: Using Yup on React Native throws unhandled promise rejection warning when validation fails

[cameronmurphy]

🐛 Bug report

Current behavior

About 1 or 2 seconds after validation fails a promise is rejected with the errors object.

Possible Unhandled Promise Rejection (id: 0):
Object {
  "test": "test is a required field",
}

Expected behavior

I'd expect no unhandled promise rejections.

Reproducible example

Steps to reproduce:

npm install -g expo-cli
expo init formik-yup-test
cd formik-yup-test
yarn add formik yup

Copy this code into App.js

import { Button, StyleSheet, Text, TextInput, View } from 'react-native';
import { Formik } from 'formik';
import * as Yup from 'yup';
import React from 'react';

const schema = Yup.object().shape({
  test: Yup.string().required(),
});

export default function App() {
  return (
    <View style={styles.container}>
      <Formik initialValues={{ test: '' }} onSubmit={values => console.log(values)} validationSchema={schema}>
        {({ errors, handleChange, handleBlur, handleSubmit, values }) => (
          <>
            <TextInput
              onBlur={handleBlur('test')}
              onChangeText={handleChange('test')}
              style={styles.textInput}
              value={values.test}
            />
            <Text style={styles.errors}>{JSON.stringify(errors)}</Text>
            <Button onPress={handleSubmit} title="Submit" />
          </>
        )}
      </Formik>
    </View>
  );
}

const styles = StyleSheet.create({
  errors: {
    textAlign: 'center',
  },
  textInput: {
    alignSelf: 'stretch',
    borderColor: 'black',
    borderWidth: 1,
    fontSize: 20,
    marginBottom: 10,
  },
  container: {
    flex: 1,
    backgroundColor: '#fff',
    padding: 20,
  },
});

Run yarn start and open in the iOS Simulator.

Suggested solution(s)

Avoid rejecting promises or document how the user can avoid this warning. The example form was based on the documentation here https://jaredpalmer.com/formik/docs/guides/react-native

Your environment

| Software | Version(s) |
| ---------------- | ---------- |
| Formik | 2.0.7 |
| Yup | 0.27.0 |
| React | 16.9 |
| npm/Yarn | Yarn 1.19.2 |
| Operating System | macOS 10.15.1 |

[dennis-tagomi]

this is caused by combineErrors and has been rolled back in 2.0.8 hotfix

[jaredpalmer]

Fixed in 2.1