Cannot read property '_init' of null vue-cropperjs

I have a project that works for Laravel + VueJs. But I am beginner and my skills in using Vue are too low. In this project i have to use cropper-js (https://github.com/fengyuanchen/cropperjs#cropperjs). I found an implementation this library special for vue-js (https://github.com/Agontuk/vue-cropperjs). I copied from package.json one string

"vue-cropperjs": "https://github.com/Agontuk/vue-cropperjs.git#master"

and execute

npm install

than, in my app.js, i wrote

import VueCropper from 'vue-cropperjs'; Vue.use(VueCropper);

and after start the application, in console, i see next text

Cannot read property '_init' of null

Also i tried use that code directly in the component file

<template>
<div class="col-md-12">
    <input type="file" name="image" accept="image/*"
           style="font-size: 1.2em; padding: 10px 0;"
           @change="setImage($event)"
    />
</div>
</template>
<script>
    import VueCropper from 'vue-cropperjs';
    export default {
        name : 'userfiles',
        data: function(){
        return {
            imgSrc: '',
            cropImg: ''
        }
    },
    methods:{
        setImage(e){
            const file = e.target.files[0];
            if (!file.type.includes('image/')) {
                alert('Please select an image file');
                return;
            }
            if(typeof FileReader === 'function'){
                const reader = new FileReader();
                reader.onload = (event) => {
                    this.imgSrc = event.target.result;
                    this.cropper.replace(event.target.result);
                };
                reader.readAsDataURL(file);
            }else{
                alert('Sorry, FileReader API not supported');
                }
            }
        }
    }
</script>

this code i copied from here (https://github.com/Agontuk/vue-cropperjs/blob/master/example/src/App.js).

but now i get

Cannot read property 'replace' of undefined

Anybody can tell what the error is and what I'm doing wrong?

It seem like you are not directly copy the source. The line this.cropper.replace(event.target.result); causes the error. There is no copper as props/data/method/computed/ref etc in your component.

In the source, there is a render function which <vue-cropper ref='cropper' ...> and later the code use this reference this.$refs.cropper. You can find more information about ref here.