ViewCollection: fix crash when clicking options while still loading.

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

@@ -4,6 +4,7 @@ import android.content.DialogInterface
 import android.os.Bundle
 import android.view.*
 import android.widget.TextView
+import android.widget.Toast
 import androidx.appcompat.app.AlertDialog
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
@@ -108,7 +109,11 @@ class ViewCollectionFragment : Fragment() {
     }
 
     override fun onOptionsItemSelected(item: MenuItem): Boolean {
-        val cachedCollection = collectionModel.value!!
+        val cachedCollection = collectionModel.value
+        if (cachedCollection == null) {
+            Toast.makeText(context, R.string.loading_error_title, Toast.LENGTH_LONG).show()
+            return super.onOptionsItemSelected(item)
+        }
 
         when (item.itemId) {
             R.id.on_edit -> {