Partially fix iOS 13 scroll bug

Signal/src/ViewControllers/ConversationView/ConversationViewController.m

@@ -4689,10 +4689,14 @@ typedef enum : NSUInteger {
 - (CGPoint)collectionView:(UICollectionView *)collectionView
     targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset
 {
-    if (self.menuActionsViewController != nil) {
+    if (@available(iOS 13, *)) {
-        NSValue *_Nullable contentOffset = [self contentOffsetForMenuActionInteraction];
+        
-        if (contentOffset != nil) {
+    } else {
-            return contentOffset.CGPointValue;
+        if (self.menuActionsViewController != nil) {
+            NSValue *_Nullable contentOffset = [self contentOffsetForMenuActionInteraction];
+            if (contentOffset != nil) {
+                return contentOffset.CGPointValue;
+            }
         }
     }