src/vs/workbench/api/common/extHostTypes.ts/NotebookCellOutputItem/constructor
class NotebookCellOutputItem:	constructor(
		public data: Uint8Array,
		public mime: string,
	) {
		const mimeNormalized = normalizeMimeType(mime, true);
		if (!mimeNormalized) {
			throw new Error('INVALID mime type, must not be empty or falsy: ' + mime);
		}
		this.mime = mimeNormalized;
	}