.catch() is catching all errors even from another promise by fetch()

I have created a simple function to authenticate users by their stored tokens, that function is based on a promise which returns a response with user details if it was successfully connected to our server API, if there's a server connection, it will return a promise rejection with specified error by React-native fetch method.

import React, { Component } from 'react';
import {
    Text,
    View,
    AlertIOS,
} from 'react-native';

function AuthAPI(token)
{
    return new Promise((resolve, reject) => {
        fetch("https://myawesomeapi.com/auth", {
            method: "POST",
            body: '{"token": "' + token + '"}',
        })
        .then((response) => response.json())
        .then((response) => {
            resolve(response);
        })
        .catch((error) => {
            reject(error);
        });
    });
}

export default class Home extends Component
{
    constructor(props)
    {
        super(props);
        this.state = {
            bodyMessage: 'Waiting for response!',
        };
    }

    componentWillMount()
    {
        AuthAPI("token-here")
        .then((response) => {
            const justAnotherVar = iamNotExist; // this will throw an error in next .catch
            AlertIOS.alert("Your Name: " + response.userFullName);
            this.setState({bodyMessage: 'Fetch is done with a response!'});
        })
        .catch((error) => {
            console.err(error);
        });
    }

    render()
    {
        const { bodyMessage } = this.state;
        return (
            <View style={{
                flex: 1,
                justifyContent: 'center',
                alignItems: 'center',
            }}>
                <Text>Welcome..</Text>
                <Text>{bodyMessage}</Text>
            </View>
        );
    }
}

Problem explanation:

When there's an error inside AuthAPI.then(/***/), it will be caught by AuthAPI.catch but as I understand AuthAPI.catch will only catch errors returned by react-native fetch method errors from that promise rejection.

For example, inside AuthAPI.then, I have assigned an undefined variable to a new constant variable const justAnotherVar = iamNotExist; so that will throw an error in the next catch.

ReferenceError: Can't find variable: iamNotExist

What I want is to keep AuthAPI.catch getting fetch method errors only and get regular red screen with specified error when there's an error inside AuthAPI.then(/***/)