I am having the same issue.
Deprecated: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in C:\xampp\htdocs\dae\wp-includes\class-wp-block-parser.php on line 256
Deprecated: strlen(): Passing null to parameter #1 ($string) of type string is deprecated in C:\xampp\htdocs\dae\wp-includes\class-wp-block-parser.php on line 333
