Unclear error situation after sending email pdfs. [info] de.systopia.donrec: invalid snapshot id detected! (0)

[being-peace]

Thanks for the donrec extension!

I am using:
Wordpress: 5.8.2
CiviCRM: 5.41.2
Donation Receipts: Version 2.1-dev

I started processing donations, first with a PDF test creation. This run through without error.
Then I started the actual processing of donations with sending PDFs with emails.

Here I received error messages in the processing details:

Datum 	Typ 	Nachricht
2022-03-29 22:59:03 	ERROR 	EMAIL processed 5 items - 4 succeeded, 1 failed
2022-03-29 22:59:06 	INFO 	EMAIL processed 5 items - 5 succeeded, 0 failed
2022-03-29 22:59:09 	ERROR 	EMAIL processed 5 items - 4 succeeded, 1 failed
2022-03-29 22:59:12 	ERROR 	EMAIL processed 5 items - 4 succeeded, 1 failed
2022-03-29 22:59:15 	INFO 	EMAIL processed 5 items - 5 succeeded, 0 failed
2022-03-29 22:59:18 	INFO 	EMAIL processed 5 items - 5 succeeded, 0 failed
2022-03-29 22:59:21 	ERROR 	EMAIL processed 5 items - 4 succeeded, 1 failed 
...

CiviCRM-Log

109160 | Mar 29 22:59:04 | [warning] hook_civicrm_donationReceiptTokenValues should be  updated to pass an array of parameter names to  CRM_Utils_Hook::invoke(). Caller:  CRM_Donrec_Logic_Hooks::donationReceiptTokenValues
109153 | Mar 29 22:59:04 | [warning] hook_civicrm_pdf_unique_token should be updated  to pass an array of parameter names to CRM_Utils_Hook::invoke(). Caller:  CRM_Utils_DonrecCustomisationHooks::pdf_unique_token
109146 | Mar 29 22:59:04 | [warning] hook_civicrm_donationReceiptTokenValues should be  updated to pass an array of parameter names to  CRM_Utils_Hook::invoke(). Caller:  CRM_Donrec_Logic_Hooks::donationReceiptTokenValues
109139 | Mar 29 22:59:03 | [warning] hook_civicrm_donationReceiptTokenValues should be  updated to pass an array of parameter names to  CRM_Utils_Hook::invoke(). Caller:  CRM_Donrec_Logic_Hooks::donationReceiptTokenValues
109132 | Mar 29 22:59:03 | [warning] hook_civicrm_pdf_unique_token should be updated  to pass an array of parameter names to CRM_Utils_Hook::invoke(). Caller:  CRM_Utils_DonrecCustomisationHooks::pdf_unique_token
109125 | Mar 29 22:59:03 | [warning] hook_civicrm_donationReceiptTokenValues should be  updated to pass an array of parameter names to  CRM_Utils_Hook::invoke(). Caller:  CRM_Donrec_Logic_Hooks::donationReceiptTokenValues
109123 | Mar 29 22:59:03 | [info] de.systopia.donrec: invalid snapshot id detected! (0)
109116 | Mar 29 22:59:03 | [warning] Deprecated function CRM_Core_OptionGroup::getValue, use CRM_Core_PseudoConstant::getKey.
109109 | Mar 29 22:59:03 | [warning] Deprecated function CRM_Core_OptionGroup::getValue, use CRM_Core_PseudoConstant::getKey.
109102 | Mar 29 22:59:03 | [warning] hook_civicrm_donationReceiptTokenValues should be  updated to pass an array of parameter names to  CRM_Utils_Hook::invoke(). Caller:  CRM_Donrec_Logic_Hooks::donationReceiptTokenValues
109095 | Mar 29 22:59:03 | [warning] hook_civicrm_pdf_unique_token should be updated  to pass an array of parameter names to CRM_Utils_Hook::invoke(). Caller:  CRM_Utils_DonrecCustomisationHooks::pdf_unique_token
109088 | Mar 29 22:59:03 | [warning] hook_civicrm_donationReceiptTokenValues should be  updated to pass an array of parameter names to  CRM_Utils_Hook::invoke(). Caller:  CRM_Donrec_Logic_Hooks::donationReceiptTokenValues
109081 | Mar 29 22:59:03 | [warning] hook_civicrm_donationReceiptTokenValues should be  updated to pass an array of parameter names to  CRM_Utils_Hook::invoke(). Caller:  CRM_Donrec_Logic_Hooks::donationReceiptTokenValues
109074 | Mar 29 22:59:03 | [warning] hook_civicrm_pdf_unique_token should be updated  to pass an array of parameter names to CRM_Utils_Hook::invoke(). Caller:  CRM_Utils_DonrecCustomisationHooks::pdf_unique_token
109067 | Mar 29 22:59:03 | [warning] hook_civicrm_donationReceiptTokenValues should be  updated to pass an array of parameter names to  CRM_Utils_Hook::invoke(). Caller:  CRM_Donrec_Logic_Hooks::donationReceiptTokenValues
109060 | Mar 29 22:59:03 | [warning] message template id should be an integer Caller: ::civicrm_api3_message_template_send

I have the same number of "de.systopia.donrec: invalid snapshot id detected! (0)" as the number of errors in the process details.

It seems that all PDFs have been generated. But what has happend? Can I know which emails have been sent?