Surface specific moderation errors for activity comments

[GaryJones]

Problem

When a group activity comment triggers WordPress's built-in link moderation (Settings → Discussion → "Hold a comment in the queue if it contains X or more links"), users see the generic error:

"There was an error posting your reply. Please try again."

BuddyBoss's own moderation layer (bp_core_check_for_moderation()) produces a specific WP_Error with the message "You have posted too many links", but this error is silently discarded before it reaches the AJAX response. The same problem affects any error originating from bp_core_check_for_moderation(), including matches against the moderation word list.

Root cause

bp_nouveau_ajax_new_activity_comment() in bp-templates/bp-nouveau/includes/activity/ajax.php calls bp_activity_new_comment() without specifying error_type, so it defaults to 'bool'.

The call chain is:

1. bp_nouveau_ajax_new_activity_comment() → bp_activity_new_comment() (error_type: 'bool')
2. bp_activity_new_comment() → bp_activity_add() (error_type: 'bool')
3. bp_activity_add() → $activity->save()
4. save() fires bp_activity_before_save → bp_activity_check_moderation_keys() → bp_core_check_for_moderation() returns WP_Error('bp_moderation_too_many_links', 'You have posted too many links')
5. The callback stores the error on $activity->errors and sets $activity->component = false to force failure
6. save() sees empty component, checks error_type — since it's 'bool', returns false (the WP_Error is discarded here)
7. false propagates back up through bp_activity_add() → bp_activity_new_comment() → the AJAX handler
8. The AJAX handler checks $bp->activity->errors['new_comment'] but this was never populated (that only happens for errors within bp_activity_new_comment() itself), so the generic fallback message is sent

Fix

Two changes in bp_nouveau_ajax_new_activity_comment():

1. Pass 'error_type' => 'wp_error' to bp_activity_new_comment() so WP_Error objects propagate through the call chain instead of being converted to false

2. Check is_wp_error( $comment_id ) on the return value and extract the actual error message for the AJAX response

The existing $bp->activity->errors['new_comment'] fallback is preserved as an elseif for backwards compatibility.

This is consistent with how bp_activity_new_comment() was designed to work — the error_type parameter has been supported since BuddyPress 2.6.0.

Steps to reproduce

1. Set Settings → Discussion → "Hold a comment in the queue if it contains 2 or more links
2. Navigate to a group activity feed
3. Post an activity comment containing 2+ links
4. Observe "There was an error posting your reply. Please try again." instead of "You have posted too many links"

Test plan

• With comment_max_links set to 2, post a group activity comment with 2+ links → should see "You have posted too many links"
• Post a comment with fewer links → should succeed normally
• Post a comment containing a moderation word list match → should see the appropriate moderation error
• Post a normal comment with no links or moderation triggers → should succeed normally

[welcome]

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