continueWithHash = hash => {
			const cache = this._fileTimestamps.get(path);
			if (cache !== undefined) {
				if (cache !== "ignore") {
					/** @type {TimestampAndHash} */
					const result = {
						.../** @type {FileSystemInfoEntry} */ (cache),
						hash
					};
					this._fileTshs.set(path, result);
					return callback(null, result);
				}
				this._fileTshs.set(path, hash);
				return callback(null, /** @type {TODO} */ (hash));
			}
			this.fileTimestampQueue.add(path, (err, entry) => {
				if (err) {
					return callback(err);
				}
				/** @type {TimestampAndHash} */
				const result = {
					.../** @type {FileSystemInfoEntry} */ (entry),
					hash
				};
				this._fileTshs.set(path, result);
				return callback(null, result);
			});
		}
@param {string} hash hash
@returns {void}