Support Forums: PHP notice in User Moderation plugin

[SergeyBiryukov]

1. Log in as a flagged user that has a pending post.
2. View that pending post.
3. You'll get two PHP notices:

   Notice: Trying to get property of non-object in wp-includes/class-wp-query.php on line 3894
   Notice: Trying to get property of non-object in wp-includes/class-wp-query.php on line 3894
   

Plugin::posts_where() calls bbp_is_single_forum() and bbp_is_single_topic(), and they both call is_singular(). The first call happens before the wp action runs, when conditional tags are not properly set up yet. See ​#wp29660, specifically ​comment 21.

Adding did_action( 'wp' ) to the condition fixes the issue and still allows flagged users to see their pending posts, which is the purpose of this code.

[coffee2code]

In 5038:

Support Forums, User Moderation: Prevent PHP notices by checking 'wp' action has happened before making checks that call is_singular().

Props SergeyBiryukov.
Fixes #2529.