PHP Notice: Undefined index

Hello,

I activated the log function the day before yesterday for a different reason.

Now I discovered the following messages there – at the same time I received an email that the three themes Twenty Nineteen, Twenty Twenty and Twenty Twenty-One have been updated automatically:

[23-Jul-2021 04:42:47 UTC] PHP Notice:  Undefined index: themes in /***/wp-content/plugins/wp-optimize/wp-optimize.php on line 135
[23-Jul-2021 04:42:47 UTC] PHP Warning:  in_array() expects parameter 2 to be array, null given in /***/wp-content/plugins/wp-optimize/wp-optimize.php on line 135
[23-Jul-2021 04:42:47 UTC] PHP Notice:  Undefined index: themes in /***/wp-content/plugins/wp-optimize/wp-optimize.php on line 135
[23-Jul-2021 04:42:47 UTC] PHP Warning:  in_array() expects parameter 2 to be array, null given in /***/wp-content/plugins/wp-optimize/wp-optimize.php on line 135
[23-Jul-2021 04:42:49 UTC] PHP Notice:  Undefined index: themes in /***/wp-content/plugins/wp-optimize/wp-optimize.php on line 135
[23-Jul-2021 04:42:49 UTC] PHP Warning:  in_array() expects parameter 2 to be array, null given in /***/wp-content/plugins/wp-optimize/wp-optimize.php on line 135
[23-Jul-2021 04:42:49 UTC] PHP Notice:  Undefined index: themes in /***/wp-content/plugins/wp-optimize/wp-optimize.php on line 135
[23-Jul-2021 04:42:49 UTC] PHP Warning:  in_array() expects parameter 2 to be array, null given in /***/wp-content/plugins/wp-optimize/wp-optimize.php on line 135
[23-Jul-2021 04:42:52 UTC] PHP Notice:  Undefined index: themes in /***/wp-content/plugins/wp-optimize/wp-optimize.php on line 135
[23-Jul-2021 04:42:52 UTC] PHP Warning:  in_array() expects parameter 2 to be array, null given in /***/wp-content/plugins/wp-optimize/wp-optimize.php on line 135
[23-Jul-2021 04:42:52 UTC] PHP Notice:  Undefined index: themes in /***/wp-content/plugins/wp-optimize/wp-optimize.php on line 135
[23-Jul-2021 04:42:52 UTC] PHP Warning:  in_array() expects parameter 2 to be array, null given in /***/wp-content/plugins/wp-optimize/wp-optimize.php on line 135