Compatibility with Wordpress 6.1x

[LTribelhorn]

I am completely aware that the sparkling theme is currently only tested with wordpress versions up to 5.8. However, it might be good to plan the changes necessary to ensure compatibility early.

The following warnings and notifications of depreciation are shown with Sparkling 2.4.9 running on Wordpress 6.1.1:

Deprecated: strpos(): Passing null to parameter #1 ($haystack) of type string is deprecated in /httpdocs/wp-includes/functions.php on line 7022 
Deprecated: str_replace(): Passing null to parameter #3 ($subject) of type array|string is deprecated in /httpdocs/wp-includes/functions.php on line 2162 
Warning: Cannot modify header information - headers already sent by (output started at /httpdocs/wp-includes/functions.php:7022) in /httpdocs/wp-admin/includes/misc.php on line 1416 
Warning: Cannot modify header information - headers already sent by (output started at /httpdocs/wp-includes/functions.php:7022) in /httpdocs/wp-includes/functions.php on line 6865 
Deprecated: Return type of Requests_Cookie_Jar::offsetExists($key) should either be compatible with ArrayAccess::offsetExists(mixed $offset): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /httpdocs/wp-includes/Requests/Cookie/Jar.php on line 63 
Deprecated: Return type of Requests_Cookie_Jar::offsetGet($key) should either be compatible with ArrayAccess::offsetGet(mixed $offset): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /httpdocs/wp-includes/Requests/Cookie/Jar.php on line 73 
Deprecated: Return type of Requests_Cookie_Jar::offsetSet($key, $value) should either be compatible with ArrayAccess::offsetSet(mixed $offset, mixed $value): void, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /httpdocs/wp-includes/Requests/Cookie/Jar.php on line 89 
Deprecated: Return type of Requests_Cookie_Jar::offsetUnset($key) should either be compatible with ArrayAccess::offsetUnset(mixed $offset): void, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /httpdocs/wp-includes/Requests/Cookie/Jar.php on line 102 
Deprecated: Return type of Requests_Cookie_Jar::getIterator() should either be compatible with IteratorAggregate::getIterator(): Traversable, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /httpdocs/wp-includes/Requests/Cookie/Jar.php on line 111 
Deprecated: http_build_query(): Passing null to parameter #2 ($numeric_prefix) of type string is deprecated in /httpdocs/wp-includes/Requests/Transport/cURL.php on line 345 
Deprecated: Return type of Requests_Utility_CaseInsensitiveDictionary::offsetExists($key) should either be compatible with ArrayAccess::offsetExists(mixed $offset): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /httpdocs/wp-includes/Requests/Utility/CaseInsensitiveDictionary.php on line 40 
Deprecated: Return type of Requests_Utility_CaseInsensitiveDictionary::offsetGet($key) should either be compatible with ArrayAccess::offsetGet(mixed $offset): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /httpdocs/wp-includes/Requests/Utility/CaseInsensitiveDictionary.php on line 51 
Deprecated: Return type of Requests_Utility_CaseInsensitiveDictionary::offsetSet($key, $value) should either be compatible with ArrayAccess::offsetSet(mixed $offset, mixed $value): void, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /httpdocs/wp-includes/Requests/Utility/CaseInsensitiveDictionary.php on line 68 
Deprecated: Return type of Requests_Utility_CaseInsensitiveDictionary::offsetUnset($key) should either be compatible with ArrayAccess::offsetUnset(mixed $offset): void, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /httpdocs/wp-includes/Requests/Utility/CaseInsensitiveDictionary.php on line 82 
Deprecated: Return type of Requests_Utility_CaseInsensitiveDictionary::getIterator() should either be compatible with IteratorAggregate::getIterator(): Traversable, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /httpdocs/wp-includes/Requests/Utility/CaseInsensitiveDictionary.php on line 91 
Warning: Cannot modify header information - headers already sent by (output started at /httpdocs/wp-includes/functions.php:7022) in /httpdocs/wp-admin/admin-header.php on line 9