Separate error cases for SNMP varbind returns

server/monitor-types/snmp.js

@@ -36,10 +36,14 @@ class SNMPMonitorType extends MonitorType {
             });
             log.debug("monitor", `SNMP: Received varbinds (Type: ${snmp.ObjectType[varbinds[0].type]} Value: ${varbinds[0].value}`);
 
-            // Verify if any varbinds were returned from the SNMP session or if the varbind type indicates a non-existent instance.
-            if (varbinds.length === 0 || varbinds[0].type === snmp.ObjectType.NoSuchInstance) {
+            // Verify if any varbinds were returned from the SNMP session.
+            if (varbinds.length === 0) {
                 throw new Error(`No varbinds returned from SNMP session (OID: ${monitor.snmpOid})`);
+            }
 
+            // Check if the varbind type indicates a non-existent instance.
+            if (varbinds[0].type === snmp.ObjectType.NoSuchInstance) {
+                throw new Error(`The SNMP query was successful but no varbinds returned for OID: ${monitor.snmpOid}`);
             }
 
             // We restrict querying to one OID per monitor, therefore `varbinds[0]` will always contain the value we're interested in.