TypeError: file.slice is not a function

[Lukas Neubert]

.../node_modules/cfb/cfb.js:370
var blob = file.slice(0,512);
                ^

TypeError: file.slice is not a function
    at parse (.../node_modules/cfb/cfb.js:370:17)
    at Object.read (.../node_modules/cfb/cfb.js:688:9)

My code is this:

const cfb = CFB.read(file, { type: 'file' })
	// const cfb = CFB.parse(data)
	const vbaDirEntry = CFB.find(cfb, 'VBA')
	if (!vbaDirEntry) {
		throw new Error('VBA root not found')
	}

	const vbaDir = CFB.read(cfb, vbaDirEntry)
	const modules = {}
	for (const entry of vbaDir.FullPaths) {
		console.log(entry)
	}