Assert flat-list sequential data

Deals with vector-of-maps vs map-of-maps issues, e.g. map-of-maps hangs with
bad errors from React Native side

src/status_im/components/list/views.cljs

@@ -86,6 +86,7 @@
   "A wrapper for FlatList.
    See https://facebook.github.io/react-native/docs/flatlist.html"
   [{:keys [data render-fn empty-component] :as props}]
+  {:pre [(sequential? data)]}
   (if (and (empty? data) empty-component)
     ;; TODO(jeluard) remove when native :ListEmptyComponent is supported
     empty-component