add try-catch to demo auth middleware (#1044)

- Since we validate email used in auth the route function needs to
  handle the possibility that userService.loginUserWithoutPassword can
  throw.

src/lib/middleware/demo-authentication.ts

@@ -9,7 +9,11 @@ function demoAuthentication(
 ): void {
     app.post(`${basePath}/api/admin/login`, async (req, res) => {
         const { email } = req.body;
-        const user = await userService.loginUserWithoutPassword(email, true);
+        try {
+            const user = await userService.loginUserWithoutPassword(
+                email,
+                true,
+            );
             const session = req.session || {};
             // @ts-ignore
             session.user = user;
@@ -19,6 +23,11 @@ function demoAuthentication(
                 // @ts-ignore
                 .json(req.session.user)
                 .end();
+        } catch (e) {
+            res.status(400)
+                .json({ error: `Could not sign in with ${email}` })
+                .end();
+        }
     });
 
     app.use(`${basePath}/api/admin/`, (req, res, next) => {