MasterTabBarController: Add sanity checks when add or remove a session. Fix runtime issue with Xcode 12.5 and NSArray mismatch type with Swift (see https://forums.swift.org/t/objective-c-interoperability-type-mismatch/12464 for more information).

Riot/Modules/TabBar/MasterTabBarController.m

@@ -356,6 +356,12 @@
 
 - (void)addMatrixSession:(MXSession *)mxSession
 {
+    if ([mxSessionArray containsObject:mxSession])
+    {
+        MXLogDebug(@"MasterTabBarController already has %@ in mxSessionArray", mxSession)
+        return;
+    }
+    
     // Check whether the controller'€™s view is loaded into memory.
     if (self.homeViewController)
     {
@@ -394,6 +400,12 @@
 
 - (void)removeMatrixSession:(MXSession *)mxSession
 {
+    if (![mxSessionArray containsObject:mxSession])
+    {
+        MXLogDebug(@"MasterTabBarController does not contain %@ in mxSessionArray", mxSession)
+        return;
+    }
+    
     [recentsDataSource removeMatrixSession:mxSession];
     
     // Check whether there are others sessions