chore: fix the failing user destroy for admin (#3223)

- fix the invitee association on the user
- handle Instagram events with inbox missing

app/services/instagram/message_text.rb

@@ -17,6 +17,9 @@ class Instagram::MessageText < Instagram::WebhooksBaseService
                                  [@messaging[:recipient][:id], @messaging[:sender][:id]]
                                end
     inbox_channel(instagram_id)
+    # person can connect the channel and then delete the inbox
+    return if @inbox.blank?
+
     ensure_contact(contact_id)
 
     create_message

app/services/instagram/webhooks_base_service.rb

@@ -3,7 +3,7 @@ class Instagram::WebhooksBaseService
 
   def inbox_channel(instagram_id)
     messenger_channel = Channel::FacebookPage.where(instagram_id: instagram_id)
-    @inbox = ::Inbox.find_by!(channel: messenger_channel)
+    @inbox = ::Inbox.find_by(channel: messenger_channel)
   end
 
   def find_or_create_contact(user)