handle unsupported file types

app/javascript/application.js

@@ -76,6 +76,7 @@ window.customElements.define('template-builder', class extends HTMLElement {
       template: reactive(JSON.parse(this.dataset.template)),
       backgroundColor: '#faf7f5',
       withPhone: this.dataset.withPhone === 'true',
+      acceptFileTypes: this.dataset.acceptFileTypes,
       isDirectUpload: this.dataset.isDirectUpload === 'true'
     })