ErrorHandlerTest::testErrorHandler in core/modules/system/tests/src/Functional/System/ErrorHandlerTest.php
Tests the error handler.
error_displayable in core/includes/errors.inc
Determines whether an error should be displayed.
LoggingForm::buildForm in core/modules/system/src/Form/LoggingForm.php
ManageFieldsTest::setUp in core/modules/field_ui/tests/src/Functional/ManageFieldsTest.php
UncaughtExceptionTest::testUncaughtException in core/tests/Drupal/FunctionalTests/Bootstrap/UncaughtExceptionTest.php
Tests uncaught exception handling when system is in a bad state.
_drupal_get_error_level in core/includes/errors.inc
Returns the current error level.