fix: npe init of remote share repository

Signed-off-by: alperozturk <[email protected]>

Author: alperozturk96

app/src/main/java/com/owncloud/android/ui/fragment/FileDetailSharingFragment.java

@@ -162,7 +162,17 @@ public void onCreate(@Nullable Bundle savedInstanceState) {
     }
 
     private void fetchSharees() {
-        ShareRepository shareRepository = new RemoteShareRepository(fileActivity.getClientRepository(), fileActivity, fileDataStorageManager);
+        final var activity = fileActivity;
+        if (activity == null) {
+            return;
+        }
+
+        final var clientRepository = activity.getClientRepository();
+        if (clientRepository == null) {
+            return;
+        }
+
+        ShareRepository shareRepository = new RemoteShareRepository(clientRepository, activity, fileDataStorageManager);
         shareRepository.fetchSharees(file.getRemotePath(), () -> {
             refreshCapabilitiesFromDB();
             refreshSharesFromDB();