src/vs/workbench/contrib/notebook/browser/view/cellParts/cellDragRenderer.ts/CodeCellDragImageRenderer/getDragImage
class CodeCellDragImageRenderer:	getDragImage(templateData: BaseCellRenderTemplate, editor: ICodeEditor, type: 'code' | 'markdown'): HTMLElement {
		let dragImage = this.getDragImageImpl(templateData, editor, type);
		if (!dragImage) {
			// TODO@roblourens I don't think this can happen
			dragImage = document.createElement('div');
			dragImage.textContent = '1 cell';
		}

		return dragImage;
	}