Check hexSerialNumber on serial numbers from onus.

src/App/Service/Huawei/HuaweiService.php

@@ -92,6 +92,7 @@ class HuaweiService
 
             $serialNumbers = $this->snmpService->getSNMP($this->snmpLibrary,"onuSerialNumber", "onuScan", $this->output);
             foreach ($serialNumbers as $index => $hexSerialNumber) {
+                if (strlen($hexSerialNumber) != 16) continue;
                 $vendoId = OnuHelper::hex2str(substr($hexSerialNumber, 0, 8));
                 $rest = substr($hexSerialNumber, 8);