Make sure the notes are an array to start with.

src/ConversationDB.php

@@ -93,8 +93,7 @@ class ConversationDB extends DB
                 )
                ');
             $active = 'active';
-            //$notes = json_encode('');
-            $notes      = '""';
+            $notes  = '[]';
             $created_at = self::getTimestamp();
 
             $sth->bindParam(':status', $active);