fix a warning if no options present

lib/AccountManager/App.pm

@@ -131,7 +131,8 @@ sub new {
             host     => $self->{configuration}->{database}->{host},
             username => $self->{configuration}->{database}->{username},
             password => $self->{configuration}->{database}->{password},
-            options  => [ split(/, */, $self->{configuration}->{database}->{options}) ]
+            options  => $self->{configuration}->{database}->{options} ?
+                [ split(/, */, $self->{configuration}->{database}->{options}) ] : undef,
         );
     }