TYPO3 Core

I get the following Exception if I want to edit the newsletter data of a new intern page newsletter:

Core: Exception handler (WEB): Uncaught TYPO3 Exception: #1437656456: $uid must be positive integer, 0 given (tablename: sys_dmail) | InvalidArgumentException thrown in file .../typo3_src-8.7.17/typo3/sysext/backend/Classes/Form/FormDataProvider/AbstractDatabaseRecordProvider.php in line 42. Requested URL: .../typo3/index.php?route=%2Frecord%2Fedit&token=--AnonymizedToken--&edit[sys_dmail][]=edit&returnUrl=%2Ftypo3%2Findex.php%3FM%3DDirectMailNavFrame_DirectMail%26moduleToken%3Dae42e994cd9572c3cfad3c59af1777b269b2e251%26id%3D262%26CMD%3Dinfo%26sys_dmail_uid%3D%26fetchAtOnce%3D1

I found out, that the check, if the uid is > 0 prevents the error.

So I've added this check to the file:
/typo3/sysext/backend/Classes/Form/FormDataProvider/DatabaseEditRow.php

from row 39 ff.:

if ($result['vanillaUid']>0){
...
}