Fix the PDO::quote() null deprecation in Idiorm query logging on PHP 8.1+ #598

Summary

On PHP 8.1 and newer, a query with a NULL bound parameter raises a deprecation when Idiorm logs it. Quantum's error handler turns a reported deprecation into an exception, so the query fails. Found while raising the minimum PHP version (#595).

Current state

• Query logging is on in debug mode (IdiormDbal::getBaseConfig() sets logging to is_debug_mode()), and lastQuery(), queryLog() and the debug toolbar's queries tab depend on it.
• Idiorm 1.5.8 (the last release) builds the logged query with array_map([$db, 'quote'], $parameters) in _log_query(). With a NULL parameter that is PDO::quote(null), which PHP 8.1 deprecates: "Passing null to parameter beautifying #1 ($string) of type string is deprecated".
• ErrorHandler::handleError() throws an ErrorException for every reported error, deprecations included. PHP reports them by default in development (error_reporting = E_ALL).
• Result: on 8.1+, in debug mode, any query that binds NULL throws.

Evidence

• Running the test suite on PHP 8.1 with deprecations reported fails 50 tests with this message; the same run on PHP 8.0 passes.
• The normal suite does not show it, because phpunit.xml sets error_reporting to E_ALL & ~E_DEPRECATED.

Why it cannot be fixed with a subclass

Idiorm calls its logging as self::_log_query(), so overriding the method in a subclass has no effect.

Proposed direction

Decide how ErrorHandler should treat E_DEPRECATED and E_USER_DEPRECATED. A deprecation is a warning about the future, not a failure, so reporting it (for example logging it) instead of throwing keeps applications running on newer PHP versions. To be agreed in this ticket.

Acceptance criteria

• a debug-mode query with a NULL parameter works on PHP 8.1 and newer with deprecations reported
• the behavior for deprecations is covered by a test that fails before the fix
• if the error handler changes, the docs for the Tracer package describe it
• composer test, composer cs:check, composer phpstan and composer rector:check pass

Notes

Relevant code: src/Tracer/ErrorHandler.php, src/Database/Adapters/Idiorm/IdiormDbal.php, phpunit.xml.