i add new NetApp storage model A250 firmware 9.13.1P3 got problem when discovery device.

example:

Unsupported operand types: int + string in /opt/observium/includes/discovery/inventory/netapp-mib.inc.php:76

Stack trace:

#0: (unknown function) called at [/opt/observium/includes/discovery/inventory/netapp-mib.inc.php:76]
71: // NETAPP-MIB::enclPowerSuppliesPartNos.1 = STRING: 114-00148+F1, 114-00148+F1
72: $parts = explode(', ', $part['enclPowerSuppliesPresent']);
73: $serials = explode(', ', $part['enclPowerSuppliesSerialNos']);
74: $nos = explode(', ', $part['enclPowerSuppliesPartNos']);
75: foreach ($parts as $i => $num) {
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