Add 404 page

ui/src/App.tsx

@@ -34,6 +34,7 @@ import TasksView from "./views/TasksView";
 import SettingsView from "./views/SettingsView";
 import ServersView from "./views/ServersView";
 import RedisInfoView from "./views/RedisInfoView";
+import PageNotFoundView from "./views/PageNotFoundView";
 
 const drawerWidth = 220;
 
@@ -273,9 +274,12 @@ function App(props: ConnectedProps<typeof connector>) {
                 <Route exact path={paths.SETTINGS}>
                   <SettingsView />
                 </Route>
-                <Route path={paths.HOME}>
+                <Route exact path={paths.HOME}>
                   <DashboardView />
                 </Route>
+                <Route path="*">
+                  <PageNotFoundView />
+                </Route>
               </Switch>
             </div>
           </main>

ui/src/views/PageNotFoundView.tsx

@@ -0,0 +1,37 @@
+import React from "react";
+import Container from "@material-ui/core/Container";
+import { makeStyles } from "@material-ui/core/styles";
+import Grid from "@material-ui/core/Grid";
+import Typography from "@material-ui/core/Typography";
+
+const useStyles = makeStyles((theme) => ({
+  container: {
+    paddingTop: theme.spacing(4),
+    paddingBottom: theme.spacing(4),
+  },
+  headingText: {
+    fontWeight: "bold",
+  },
+}));
+
+export default function PageNotFoundView() {
+  const classes = useStyles();
+  return (
+    <Container maxWidth="lg" className={classes.container}>
+      <Grid container spacing={3}>
+        <Grid item xs={12}>
+          <Typography
+            variant="h5"
+            align="center"
+            className={classes.headingText}
+          >
+            Oops!
+          </Typography>
+          <Typography variant="subtitle1" color="textSecondary" align="center">
+            404 - Page Not Found
+          </Typography>
+        </Grid>
+      </Grid>
+    </Container>
+  );
+}

ui/src/views/RedisInfoView.tsx

@@ -18,12 +18,6 @@ const useStyles = makeStyles((theme) => ({
     paddingTop: theme.spacing(4),
     paddingBottom: theme.spacing(4),
   },
-  paper: {
-    padding: theme.spacing(2),
-    display: "flex",
-    overflow: "auto",
-    flexDirection: "column",
-  },
 }));
 
 function mapStateToProps(state: AppState) {