ERROR ReferenceError: KEYUTIL is not defined - identityserver4

Question

I have been following this tutorial and so far so good except that I keep getting this error after a successful login or what seems like it
ERROR ReferenceError: KEYUTIL is not defined
at OidcSecurityValidation.validate_signature_id_token (oidc.security.validation.ts:152)
at SafeSubscriber._next (oidc.security.service.ts:116)
at SafeSubscriber.__tryOrUnsub (Subscriber.js:238)
at SafeSubscriber.next (Subscriber.js:185)
at Subscriber._next (Subscriber.js:125)
at Subscriber.next (Subscriber.js:89)
at CatchSubscriber.Subscriber._next (Subscriber.js:125)
at CatchSubscriber.Subscriber.next (Subscriber.js:89)
at MapSubscriber._next (map.js:83)
at MapSubscriber.Subscriber.next (Subscriber.js:89)
defaultErrorLogger # core.es5.js:1084
ErrorHandler.handleError # core.es5.js:1144
next # core.es5.js:4778
schedulerFn # core.es5.js:3851
SafeSubscriber.__tryOrUnsub # Subscriber.js:238
SafeSubscriber.next # Subscriber.js:185
Subscriber._next # Subscriber.js:125
Subscriber.next # Subscriber.js:89
Subject.next # Subject.js:55
EventEmitter.emit # core.es5.js:3837
NgZone.triggerError # core.es5.js:4209
onHandleError # core.es5.js:4170
ZoneDelegate.handleError # zone.js:395
Zone.runTask # zone.js:194
ZoneTask.invoke # zone.js:486
I tried the approach specified in the tutorial that didnt work. I imported the file this way import "./assets/jsrsasign.min.js" in vendor.ts it didnt help either.

Answer 1

Ok so here is what I did to get through. If you are using webpack 2 (that is what I am using)
add the following (depending on your folder arrangements)
new CopyWebpackPlugin([
{ from: './angularApp/assets/*.*', to: 'assets/', flatten: true }
]),
and then referencing in my index.html like this
<script src="assets/jsrsasign.min.js"></script>
the last line in the section