Edit collection fragment: fix crash.

app/src/main/java/com/etesync/syncadapter/ui/etebase/EditCollectionFragment.kt

@@ -238,12 +238,15 @@ class EditCollectionFragment : Fragment() {
                     }
                 } catch (e: EtebaseException) {
                     uiThread {
+                        val context = context
+                        if (context != null) {
                             AlertDialog.Builder(requireContext())
                                     .setIcon(R.drawable.ic_info_dark)
                                     .setTitle(R.string.exception)
                                     .setMessage(e.localizedMessage)
                                     .setPositiveButton(android.R.string.yes) { _, _ -> }.show()
                         }
+                    }
                 } finally {
                     uiThread {
                         loadingModel.setLoading(false)