Vue js keep returning "Unknown custom element" - vue.js

Question

I'm sure i didn't type anything wrong in my code, because i didn't even change it, but i just keep getting Unknown custom element error in console, here is my code:
app.js
/**
* First we will load all of this project's JavaScript dependencies which
* includes Vue and other libraries. It is a great starting point when
* building robust, powerful web applications using Vue and Laravel.
*/
require('./bootstrap');
window.Vue = require('vue');
/**
* Next, we will create a fresh Vue application instance and attach it to
* the page. Then, you may begin adding components to this application
* or customize the JavaScript scaffolding to fit your unique needs.
*/
Vue.component('example-component', require('./components/ExampleComponent.vue'));
const app = new Vue({
el: "#app"
});
ExampleComponent.vue
<template>
<div class="container">
<div class="row justify-content-center">
<div class="col-md-8">
<div class="card card-default">
<div class="card-header">Example Component</div>
<div class="card-body">
I'm an example component.
</div>
</div>
</div>
</div>
</div>
</template>
<script>
export default {
mounted() {
console.log('Component mounted.')
}
}
</script>

Answer 1

Main File
require('./bootstrap');
window.Vue = require('vue');
<template>
<example-component></example-component>
</template>
/**
* Next, we will create a fresh Vue application instance and attach it to
* the page. Then, you may begin adding components to this application
* or customize the JavaScript scaffolding to fit your unique needs.
*/
Vue.component('example-component', require('./components/ExampleComponent.vue'));
const app = new Vue({
el: "#app"
});
<template>
<div class="container">
<div class="row justify-content-center">
<div class="col-md-8">
<div class="card card-default">
<div class="card-header">Example Component</div>
<div class="card-body">
I'm an example component.
</div>
</div>
</div>
</div>
</div>
</template>
<script>
export default {
mounted() {
console.log('Component mounted.')
}
}
</script>