Fix don't inspect systemContact if not defined (#634)

src/partials/messenger.ts

@@ -1275,8 +1275,10 @@ class ReceiverDetailController {
 
             this.contactService.requiredDetails(contactReceiver)
                 .then(() => {
-                    this.hasSystemEmails = contactReceiver.systemContact.emails.length > 0;
-                    this.hasSystemPhones = contactReceiver.systemContact.phoneNumbers.length > 0;
+                    this.hasSystemEmails = contactReceiver.systemContact !== undefined
+                        && contactReceiver.systemContact.emails.length > 0;
+                    this.hasSystemPhones = contactReceiver.systemContact !== undefined &&
+                        contactReceiver.systemContact.phoneNumbers.length > 0;
                 })
                 .catch((error) => {
                     // TODO: Redirect or show an alert?

src/services/webclient.ts

@@ -2181,9 +2181,10 @@ export class WebClientService {
         // Set contact detail
         const contactReceiver = this.receivers.contacts
             .get(args[WebClientService.ARGUMENT_IDENTITY]) as threema.ContactReceiver;
-        if (hasValue(data[WebClientService.SUB_TYPE_RECEIVER])) {
+        const receiver = data[WebClientService.SUB_TYPE_RECEIVER];
+        if (hasValue(receiver)) {
             contactReceiver.systemContact =
-                data[WebClientService.SUB_TYPE_RECEIVER][WebClientService.ARGUMENT_SYSTEM_CONTACT];
+                receiver[WebClientService.ARGUMENT_SYSTEM_CONTACT];
         }
         future.resolve(contactReceiver);
     }