PHP 8.1 require to declare a return type. When not doing so, the notice is printed.
A simple workaround might be using the `#[\ReturnTypeWillChange]` attribute to suppress the error message; cf rARC3626582354e4fc62191927a80b274ec71284cb77.
Output from PHPStan:
* https://we.phorge.it/source/phorge/browse/master/src/applications/fact/extract/PhabricatorFactUpdateIterator.php$36
** Return type mixed of method `PhabricatorFactUpdateIterator::key()` is not covariant with tentative return type mixed of method `Iterator::key()`. Make it covariant, or use the `#[\ReturnTypeWillChange]` attribute to temporarily suppress the error.
* https://we.phorge.it/source/phorge/browse/master/src/applications/harbormaster/storage/build/HarbormasterBuildLogChunkIterator.php$21
```** Return type mixed of method `HarbormasterBuildLogChunkIterator::key()` is not covariant with tentative return type mixed of method `Iterator::key()`. Make it covariant, or use the `#[\ReturnTypeWillChange]` attribute to temporarily suppress the error.
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Line /var/www/html/phorge/phorge/src/applications/fact/extract/PhabricatorFactUpdateIterator.php
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36 Return type mixed of method PhabricatorFactUpdateIterator::key() is not covariant with tentative return type mixed of method Iterator::key().
? Make it covariant, or use the #[\ReturnTypeWillChange] attribute to temporarily suppress the error.
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Line /var/www/html/phorge/phorge/src/applications/harbormaster/storage/build/HarbormasterBuildLogChunkIterator.php
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21 Return type mixed of method HarbormasterBuildLogChunkIterator::key() is not covariant with tentative return type mixed of method Iterator::key().
? Make it covariant, or use the #[\ReturnTypeWillChange] attribute to temporarily suppress the error.
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Line /var/www/html/phorge/phorge/src/infrastructure/storage/lisk/LiskMigrationIterator.php* https://we.phorge.it/source/phorge/browse/master/src/infrastructure/storage/lisk/LiskMigrationIterator.php$29
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29 ** Return type mixed of method `LiskMigrationIterator::key()` is not covariant with tentative return type mixed of method `Iterator::key().
?`. Make it covariant, or use the #[\ReturnTypeWillChange] attribute to temporarily suppress the error.
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Line /var/www/html/phorge/phorge/src/infrastructure/storage/lisk/LiskRawMigrationIterator.phpor use the `#[\ReturnTypeWillChange]` attribute to temporarily suppress the error.
* https://we.phorge.it/source/phorge/browse/master/src/infrastructure/storage/lisk/LiskRawMigrationIterator.php$19
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19 ** Return type mixed of method `LiskRawMigrationIterator::key()` is not covariant with tentative return type mixed of method `Iterator::key().
?`. Make it covariant, or use the #[\ReturnTypeWillChange] attribute to temporarily suppress the error.
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Line /var/www/html/phorge/phorge/src/infrastructure/storage/lisk/PhabricatorQueryIterator.phpor use the `#[\ReturnTypeWillChange]` attribute to temporarily suppress the error.
* https://we.phorge.it/source/phorge/browse/master/src/infrastructure/storage/lisk/PhabricatorQueryIterator.php$21
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21 ** Return type mixed of method `PhabricatorQueryIterator::key()` is not covariant with tentative return type mixed of method `Iterator::key().
?`. Make it covariant, or use the #[\ReturnTypeWillChange] attribute to temporarily suppress the error.
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```or use the `#[\ReturnTypeWillChange]` attribute to temporarily suppress the error.