Tests fail under NodeJS v18

[DougReeder]

Both the test and test:mocha scripts fail under node 18 with the error: ReferenceError: FileReader is not defined

changing
if (typeof Blob === 'undefined') {
to if (typeof Blob === 'undefined' || typeof FileReader === 'undefined') {
at line 248 of util.ts fixes this for test:mocha, but then test throws

UnhandledPromiseRejection: This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). The promise rejected with the reason "[object Object]".