IOS-6907 T4624488 Fix crash when tapping shared items with no shares

(cherry picked from commit 86fd381)

Author: gmagpayo

iMEGA/Node/Shared Items/SharedItemsViewController+Additions.swift

@@ -169,10 +169,12 @@ extension SharedItemsViewController {
 
         var isEnabled = false
         if incomingButton?.isSelected == true {
-            isEnabled = incomingShareList.size.intValue > 0 ||
-                        incomingUnverifiedShareList.size.intValue > 0
+            let inShareSize = incomingShareList?.size.intValue ?? 0
+            let unverifiedInShareSize = incomingUnverifiedShareList?.size.intValue ?? 0
+            isEnabled = inShareSize > 0 || unverifiedInShareSize > 0
         } else if outgoingButton?.isSelected == true {
-            isEnabled = outgoingShareList.size.intValue > 0
+            let outShareSize = outgoingShareList?.size.intValue ?? 0
+            isEnabled = outShareSize > 0
         } else if linksButton?.isSelected == true {
             isEnabled = publicLinksArray.isNotEmpty
         }

iMEGA/Node/Shared Items/SharedItemsViewController.h

@@ -29,13 +29,13 @@ NS_ASSUME_NONNULL_BEGIN
 @property (weak, nonatomic) IBOutlet UIView *outgoingLineView;
 @property (weak, nonatomic) IBOutlet UIView *linksLineView;
 
-@property (nonatomic, strong) MEGAShareList *outgoingShareList;
+@property (nonatomic, strong, nullable) MEGAShareList *outgoingShareList;
 @property (nonatomic, strong, nullable) MEGAShareList *outgoingUnverifiedShareList;
 @property (nonatomic, strong, nullable) NSMutableArray<MEGAShare *> *outgoingUnverifiedSharesMutableArray;
 @property (nonatomic, strong, nullable) NSMutableArray<MEGANode *> *outgoingUnverifiedNodesMutableArray;
 
-@property (nonatomic, strong) MEGAShareList *incomingShareList;
-@property (nonatomic, strong) MEGAShareList *incomingUnverifiedShareList;
+@property (nonatomic, strong, nullable) MEGAShareList *incomingShareList;
+@property (nonatomic, strong, nullable) MEGAShareList *incomingUnverifiedShareList;
 @property (nonatomic, strong, nullable) NSMutableArray<MEGAShare *> *incomingUnverifiedSharesMutableArray;
 @property (nonatomic, strong, nullable) NSMutableArray<MEGANode *> *incomingUnverifiedNodesMutableArray;