* 100% coverage on ErrorHandler::codeToString
* 100% coverage on ErrorHandler::registerFatalHandler
* fix typo
* covers ErrorHandler::register() and left conditions on purpose
* 100% coverage on ErrorHandler::registerErrorHandler()
* 100% coverage on ErrorHandler::registerExceptionHandler()
* Checks for possible interface breaking changes
* 100% coverage on ErrorHandler::codeToString
100% coverage on ErrorHandler::registerFatalHandler
covers ErrorHandler::register() and left conditions on purpose
100% coverage on ErrorHandler::registerErrorHandler()
100% coverage on ErrorHandler::registerExceptionHandler()