editor is null when using with sapper

[niraj-gawande]

<script>
        import CKEditor from "ckeditor5-svelte";
	// Setting up editor prop to be sent to wrapper component
	let editor ;
	// Reference to initialised editor instance
	let editorInstance = null;
	// Setting up any initial data for the editor
	let editorData = "Hello World";

	// If needed, custom editor config can be passed through to the component
	// Uncomment the custom editor config if you need to customise the editor.
	// Note: If you don't pass toolbar object then Document editor will use default set of toolbar items.
	let editorConfig = {
		toolbar: {
			items: [
				"heading",
				"|",
				"fontFamily",
				"fontSize",
				"bold",
				"italic",
				"underline",
			],
		},
	};

	onMount(async () => {
		const module = await import(
			"@ckeditor/ckeditor5-build-decoupled-document/build/ckeditor"
		);

		editor = module
		console.log('_____',editor)
	});

        function onReady({ detail: editor }) {
		// Insert the toolbar before the editable area.
		editorInstance = editor;
		editor.ui
			.getEditableElement()
			.parentElement.insertBefore(
				editor.ui.view.toolbar.element,
				editor.ui.getEditableElement()
			);
	    }

</script>

<CKEditor
							on:ready={onReady}
							bind:config={editorConfig}
							bind:value={editorData}
						/>

I am getting Uncaught (in promise) TypeError: editor is null

How to use it in sapper ?