Fix error handling when no client_id is given

Change-Id: I6e9a7b5028fc538b6d45375e5bd5858b978ad1a6
diff --git a/t/plugin/auth-oauth.t b/t/plugin/auth-oauth.t
index 53358e8..63c1df2 100644
--- a/t/plugin/auth-oauth.t
+++ b/t/plugin/auth-oauth.t
@@ -765,7 +765,11 @@
 # OAuth client authorization flow
 $t->get_ok(Mojo::URL->new('/settings/oauth/authorize'))
   ->status_is(302)
-  ->header_is('location','/settings/oauth/authorize')
+  ->header_is('location','/settings/oauth')
+  ;
+
+$t->get_ok('/settings/oauth/')
+  ->text_is('div.notify-error', 'Some fields are invalid')
   ;
 
 # Logout