Vue only works when I put braces next to return

Question

I'm starting with Vue and I'm trying to understand why this code works

<!-- HTML element -->
<div id="app">{{ message }}</div>
<!-- Script for our app -->
<script>

    const { createApp }     =   Vue

    createApp({
        data() {
            return {
                message     :   'Hello Vue'
            }
        }
    }).mount( '#app' )
</script>

and this one doesn't.

<!-- HTML element -->
<div id="app">{{ message }}</div>
<!-- Script for our app -->
<script>

    const { createApp }     =   Vue

    createApp({
        data() {
            return 
            {
                message     :   'Hello Vue'
            }
        }
    }).mount( '#app' )
</script>

Note that I only did a line jump after the return and now it doesn't work. Is it a syntax related problem?