No need to coerce a string into another string.

ui/src/hosts/containers/HostsPage.js

@@ -50,7 +50,7 @@ export const HostsPage = React.createClass({
         const reason = 'Unable to get apps for hosts'
         addFlashMessage({type: 'error', text: reason})
         this.setState({
-          hostsError: reason.toString(),
+          hostsError: reason,
           hostsLoading: false,
         })
       });