Warning: React.jsx: type is invalid

Warning: React.jsx: type is invalid -- expected a string (for built-in components) or a class/function (for composite components) but got: %s.%s%s, object,  You likely forgot to export your component from the file it's defined in, or you might have mixed up default and named imports.
Check the render method of `Calculator`., 
   in Calculator (created by App)
   in RCTView (created by View)
   in View (created by App)
   in App (created by ExpoRoot)
   in ExpoRoot
   in RCTView (created by View)
   in View (created by AppContainer)
   in DevAppContainer (created by AppContainer)
   in RCTView (created by View)
   in View (created by AppContainer)
   in AppContainer
   in main(RootComponent)

import React, { Component } from 'react';
import { View, StyleSheet, Text, StatusBar } from 'react-native';
import Button from './Button';
import Screen from './Screen';
import History from './History';

export class Calculator {
 constructor(props) {
 super(props);
 this.state = {
 expression: '',
 result: '',
 actualExpression: '',
 isHistoryVisible: false,
 isEqualPress: false,
 historyarr: [],
 };
 this.historyarrRef = React.createRef();
 }

 showHistory = () => {
 this.setState({ isHistoryVisible: true });
 };

 closeHistory = () => {
 this.setState({ isHistoryVisible: false });
 };

 getButtonPressedVal = (buttonPressed) => {
 const { expression, actualExpression, isEqualPress, result } = this.state;
 let newExpression;
 let newActalExp ;
 if (isEqualPress) {
 newExpression = `${buttonPressed}`;

 } else newExpression = `${expression}${buttonPressed}`;

 //console.log(newExpression);

 this.setState({
 expression: newExpression,
 });

 let actualChar = buttonPressed;
 if (actualChar === '÷') {
 actualChar = '/';
 } else if (actualChar === '×') {
 actualChar = '*';
 } else if (actualChar === '−') {
 actualChar = '-';
 }

 if(isEqualPress){newActalExp=`${actualChar}`}
 else{
 newActalExp = `${actualExpression}${actualChar}`;
 }
 
 this.setState({
 actualExpression: newActalExp,
 isEqualPress:false
 });

 try {
 this.setState({
 result: eval(newActalExp).toString(),
 });
 } catch (e) {
 console.log('error');
 }
 };

 allClear = () => {
 this.setState({
 expression: '',
 result: '',
 actualExpression: '',
 });
 };

 del = () => {
 const { expression, actualExpression, result, prevRes } = this.state;
 let newActalExp = actualExpression.substring(
 0,
 actualExpression.length - 1
 );
 this.setState({
 expression: expression.substring(0, expression.length - 1),
 actualExpression: newActalExp,
 });
 try {
 this.setState({
 result: eval(newActalExp).toString(),
 });
 } catch (e) {
 try {
 this.setState({
 result: eval(
 newActalExp.substring(0, expression.length - 2)
 ).toString(),
 });
 } catch (e) {
 this.setState({ expression: '', result: '', actualExpression: '' });
 }
 }
 };

 onEqualPress = () => {
 const { expression, result, historyarr, isEqualPress } = this.state;
 const hist = { expression, result };
 if (expression != '') {
 historyarr.push(hist);
 }
 this.setState({
 historyarr: historyarr,
 expression: result,
 result: '',
 isEqualPress: true,
 });
 console.log(historyarr);
 };

 clearHist = () => {
 this.setState({
 historyarr: [],
 });
 };

 render() {
 const {
 expression,
 result,
 actualExpression,
 isHistoryVisible,
 } = this.state;

 return (
 <>
 {isHistoryVisible && (
 <View style={styles.historyWrap}>
 <History
 closeHistory={this.closeHistory}
 historyarr={this.state.historyarr}
 clearHist={this.clearHist}
 />
 </View>
 )}
 <View style={styles.container}>
 <StatusBar barStyle="light-content" backgroundColor="darkred" />

 <Screen
 style={styles.screen}
 expression={expression}
 result={result}
 />
 <Button
 style={styles.button}
 getButtonPressedVal={this.getButtonPressedVal}
 allClear={this.allClear}
 del={this.del}
 showHistory={this.showHistory}
 onEqualPress={this.onEqualPress}
 />
 </View>
 </>
 );
 }
}

const styles = StyleSheet.create({
 container: {
 flex: 3,
 },
 historyWrap: {
 position: 'absolute',
 top: 5,
 zIndex: 3,
 height: '100%',
 width: '100%',
 backgroundColor: '#00000061',
 },
});

export default Calculator;