fix(server): Fix a potential NULL ptr access in ua_subscription_monitoreditem.c
fix(server): Fix a potential NULL ptr access in ua_subscription_monitoreditem.c

StalderT/open62541,jpfr/open62541,StalderT/open62541,StalderT/open62541,open62541/open62541,JGrothoff/open62541,open62541/open62541,JGrothoff/open62541,jpfr/open62541,StalderT/open62541,open62541/open62541,open62541/open62541,jpfr/open62541,JGrothoff/open62541,JGrothoff/open62541,jpfr/open62541