error_displayable($error = NULL) Determines whether an error should be displayed. When
_drupal_get_error_level() Returns the current error level. This function should
_drupal_error_handler_real($error_level, $message, $filename, $line, $context) Provides custom PHP error handling
drupal_error_levels() Maps PHP error constants to watchdog severity levels. The
_drupal_log_error($error, $fatal = FALSE) Logs a PHP error or exception and displays an error page in fatal
Functions for error handling. File core/includes/errors.inc Functions