shell: lib: handle cockpit.user() failures

In our test TestLogin.testFailingWebsocket the dbus calls fail which
fails the promise which was unhandled leading to the tests to fail due
to an unhandled exception.

pkg/lib/hooks.js

@@ -88,7 +88,7 @@ export function usePageLocation() {
 
 const cockpit_user_promise = cockpit.user();
 let cockpit_user = null;
-cockpit_user_promise.then(user => { cockpit_user = user });
+cockpit_user_promise.then(user => { cockpit_user = user }).catch(err => console.log(err));
 
 export function useLoggedInUser() {
     const [user, setUser] = useState(cockpit_user);

pkg/shell/hosts.jsx

@@ -70,7 +70,7 @@ export class CockpitHosts extends React.Component {
     componentDidMount() {
         cockpit.user().then(user => {
             this.setState({ current_user: user.name || "" });
-        });
+        }).catch(exc => console.log(exc));
     }
 
     static getDerivedStateFromProps(nextProps, prevState) {

pkg/shell/indexes.jsx

@@ -97,7 +97,7 @@ function MachinesIndex(index_options, machines, loader) {
     let current_user = "";
     cockpit.user().then(user => {
         current_user = user.name || "";
-    });
+    }).catch(exc => console.log(exc));
 
     /* Navigation */
     let ready = false;