Fix: Error handling in case of return code 502

[Rakdos8]

When a query failed in return code 502 (bad gateway), the RequestFailedException tries to fill the $message variable with a null value which is deprecated and throw a E_DEPRECATED error.

$ cat eseye-*.log | grep "bad gateway" | wc -l
550

$ cat eseye-2023-05-14.log | grep "bad gateway"
[2023-05-14T13:01:54.384626+00:00] eseye.ERROR: [http 502, bad gateway] get -> https://esi.evetech.net/latest/characters/%%REDACTED%%/wallet/?datasource=tranquility [t/e: 0.06s/]
[2023-05-14T13:26:00.975542+00:00] eseye.ERROR: [http 502, bad gateway] get -> https://esi.evetech.net/latest/markets/%%REDACTED%%/history/?datasource=tranquility&type_id=%%REDACTED%% [t/e: 0.07s/]

$ cat 2023-05-14-php_errors.log | grep "13:26:00" -A 2
[14/05/2023 13:26:00] Erreur: E_DEPRECATED (8192)
[14/05/2023 13:26:00] Exception: ErrorException
[14/05/2023 13:26:00] Message: Exception::__construct(): Passing null to parameter #1 ($message) of type string is deprecated
[14/05/2023 13:26:00] Stack trace: #0 [internal function]: ICE_Core\utils\handler\ErrorHandler::log()
#1 vendor/eveseat/eseye/src/Exceptions/RequestFailedException.php(61): Exception->__construct()
#2 vendor/eveseat/eseye/src/Fetchers/GuzzleFetcher.php(293): Seat\Eseye\Exceptions\RequestFailedException->__construct()

$ cat 2023-05-14-php_errors.log | grep "13:01:54" -A 2
[14/05/2023 13:01:54] Erreur: E_DEPRECATED (8192)
[14/05/2023 13:01:54] Exception: ErrorException
[14/05/2023 13:01:54] Message: Exception::__construct(): Passing null to parameter #1 ($message) of type string is deprecated
[14/05/2023 13:01:54] Stack trace: #0 [internal function]: ICE_Core\utils\handler\ErrorHandler::log()
#1 vendor/eveseat/eseye/src/Exceptions/RequestFailedException.php(61): Exception->__construct()
#2 vendor/eveseat/eseye/src/Fetchers/GuzzleFetcher.php(293): Seat\Eseye\Exceptions\RequestFailedException->__construct()

I'm pretty sure there is a better fix but I can't help much more at this level