fix for NaN in case of a empty multi-selection

quick fix, although I'd say that serializing the result as JSON on the java side and simply passing it on on the js side would be nicer... (could do it, if you'd be interested)

DialogAndroid.js

@@ -57,7 +57,9 @@ class DialogAndroid {
       callbacks.itemsCallbackMultiChoice = selected => {
         var indices = selected.split(',').map(x => parseInt(x));
         var elements = indices.map(ind => (finalOptions.items || [])[ind]);
-
+        if(indices.length === 1 && isNaN(indices[0])){
+          indices=[] // the case of empty selection
+        }
         originalCallback(indices, elements);
       }
     }