Merge branch 'mkirk/tap-legacy-nonblocking'

Signal/src/ViewControllers/ConversationView/MessagesViewController.m

@@ -2396,9 +2396,20 @@ typedef enum : NSUInteger {
     DDLogWarn(@"%@ Unhandled tap for error message:%@", self.tag, message);
 }
 
-- (void)tappedNonBlockingIdentityChangeForRecipientId:(NSString *)signalId
+- (void)tappedNonBlockingIdentityChangeForRecipientId:(nullable NSString *)signalId
 {
-    NSParameterAssert(signalId != nil);
+    if (signalId == nil) {
+        if (self.thread.isGroupThread) {
+            // Before 2.13 we didn't track the recipient id in the identity change error.
+            DDLogWarn(@"%@ Ignoring tap on legacy nonblocking identity change since it has no signal id", self.tag);
+        } else {
+            DDLogInfo(
+                @"%@ Assuming tap on legacy nonblocking identity change corresponds to current contact thread: %@",
+                self.tag,
+                self.thread.contactIdentifier);
+            signalId = self.thread.contactIdentifier;
+        }
+    }
 
     [self showFingerprintWithRecipientId:signalId];
 }