fix: Remove invalid session tokens + Login using the Return key

frontend/src/components/app.tsx

@@ -44,6 +44,8 @@ export default class Application extends React.Component<IProps> {
                 this.props.setUser(user);
                 this.props.setAuthenticated(true);
             }).catch(err => {
+                // The token is invalid, so we should remove it
+                removeSessionToken(window);
                 this.props.setAuthenticated(false);
             });
         }
@@ -137,6 +139,7 @@ export default class Application extends React.Component<IProps> {
     }
 
     getTopTenLearners = (): Promise<TopTen[]> => {
+        // TODO: Deprecate?
         const id = this.props.user.classId;
         return new Promise((res, rej) => {
             fetch(`${BACKEND_URL}/api/class/${id}/topTen`, {

frontend/src/pages/login.tsx

@@ -65,6 +65,13 @@ const LoginPageWithRouter = withRouter(
         }
 
         render() {
+            // Trigger a login when return is pressed
+            const onEnter = (event: any) => {
+                if (event.key === "Enter") {
+                    this.performLogin();
+                }
+            };
+
             return <div>
                 <Grid
                     container
@@ -80,12 +87,14 @@ const LoginPageWithRouter = withRouter(
                                 <Grid item>
                                     <TextField
                                         label="Username"
+                                        onKeyPress={onEnter}
                                         inputRef={node => this.usernameRef = node} />
                                 </Grid>
                                 <Grid item>
                                     <TextField
                                         label="Passwort"
                                         type="password"
+                                        onKeyPress={onEnter}
                                         inputRef={node => this.passwordRef = node} />
                                 </Grid>
                                 <Grid item>