Vue won't render custom component - vue.js

Question

I'm trying to create a custom component for some repetitive html. But the component won't show and I get this error:
[Vue warn]: You are using the runtime-only build of Vue where the template compiler is not available. Either pre-compile the templates into render functions, or use the compiler-included build.
found in
---> <Child>
<VApp>
<App> at src/App.vue
<Root>
My main.js:
import Vue from 'vue'
import App from './App.vue'
import router from './router'
import vuetify from './plugins/vuetify'
Vue.config.productionTip = false
Vue.component('child', {
props: ['text'],
template: `<div>{{ text }}<div>`
});
new Vue({
router,
vuetify,
render: h => h(App)
}).$mount('#app')
My App.vue:
<template>
<v-app>
<child :text="message"></child>
<Navbar/>
<v-content>
<router-view></router-view>
</v-content>
<Footer/>
</v-app>
</template>
<script>
import styles from './app.css'
import Navbar from '#/components/Navbar'
import Footer from '#/components/Footer'
export default {
name: 'App',
components: { Navbar, Footer },
computed: {
theme(){
return (this.$vuetify.theme.dark) ? 'dark' : 'light'
},
},
data: () => ({
//
}),
};
</script>
What is going on? How to define a custom component?
My question "has mostly code"; so, my thoughts on vue.js: I notice that there are quite a few different ways or styles to build vue.js applications. I wish their examples would give more context on where to put the example code, I'm a seasoned developer, but new to web dev and js, and find that a lack of examples on the vue.js site really makes it hard to learn this framework.

Answer 1

Try this:
1- create a component in a separate .vue file
2- register it globally in main.js
3- then call it in any component directly.
1.
<template><div>{{ text }}<div></template>
<script>
export default{
props:['text']
},
</script>
2. in main.js
//...
Vue.component('child-component',require('./path/to/chaild/compoent').default);
//...
3 Now you can call it in any component because it is registered globally.
<template>
<div>
<child-component text='some text to pass as prop.'/>
//...
</div>
</template>
//...