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: ${mime}. Must be in the format "type/subtype[;optionalparameter]"`);
		}
		this.mime = mimeNormalized;
	}