Fix nil error when removing status caused by race condition (mastodon#16099)

Author: Gargron

app/lib/status_reach_finder.rb

@@ -62,7 +62,7 @@ def replies_account_ids
   end
 
   def followers_inboxes
-    if @status.reply? && @status.thread.account.local? && @status.distributable?
+    if @status.in_reply_to_local_account? && @status.distributable?
       @status.account.followers.or(@status.thread.account.followers).inboxes
     else
       @status.account.followers.inboxes

app/models/status.rb

@@ -161,6 +161,10 @@ def local?
     attributes['local'] || uri.nil?
   end
 
+  def in_reply_to_local_account?
+    reply? && thread&.account&.local?
+  end
+
   def reblog?
     !reblog_of_id.nil?
   end

app/workers/activitypub/distribution_worker.rb

@@ -35,7 +35,7 @@ def inboxes
     # Deliver the status to all followers.
     # If the status is a reply to another local status, also forward it to that
     # status' authors' followers.
-    @inboxes ||= if @status.reply? && @status.thread.account.local? && @status.distributable?
+    @inboxes ||= if @status.in_reply_to_local_account? && @status.distributable?
                    @account.followers.or(@status.thread.account.followers).inboxes
                  else
                    @account.followers.inboxes