fix problem clicking on offer-delivery, plus some other hardening and phrasing

src/libs/util.ts

@@ -416,8 +416,10 @@ export function offerGiverDid(
  */
 export const canFulfillOffer = (
   veriClaim: GenericCredWrapper<GenericVerifiableCredential>,
+  isRegistered: boolean,
 ) => {
   return (
+    isRegistered &&
     veriClaim.claimType === "Offer" &&
     !!offerGiverDid(veriClaim as GenericCredWrapper<OfferClaim>)
   );