When user session not found, device lists can be incorrectly returned

[xmacan]

Problem is if user_id session variable is not set, user_id 0 is used. So function returns unexpected list. It causes problem in intropage.

[TheWitness]

Yea, I get it. There is more than one location though and a few components out of order.

[TheWitness]

Please review the commit.