Bug fix/handle nullptr (#7432)
Bug fix/handle nullptr (#7432)

* handle more potential nullptrs, fix try/catch scope

* fix none reply

graetzer/arangodb,fceller/arangodb,fceller/arangodb,Simran-B/arangodb,Simran-B/arangodb,graetzer/arangodb,arangodb/arangodb,Simran-B/arangodb,wiltonlazary/arangodb,graetzer/arangodb,arangodb/arangodb,Simran-B/arangodb,graetzer/arangodb,wiltonlazary/arangodb,fceller/arangodb,fceller/arangodb,arangodb/arangodb,Simran-B/arangodb,fceller/arangodb,Simran-B/arangodb,graetzer/arangodb,graetzer/arangodb,arangodb/arangodb,graetzer/arangodb,graetzer/arangodb,fceller/arangodb,graetzer/arangodb,graetzer/arangodb,fceller/arangodb,wiltonlazary/arangodb,arangodb/arangodb,wiltonlazary/arangodb,graetzer/arangodb,fceller/arangodb,graetzer/arangodb,arangodb/arangodb,arangodb/arangodb,Simran-B/arangodb,wiltonlazary/arangodb,Simran-B/arangodb,Simran-B/arangodb,arangodb/arangodb,graetzer/arangodb,fceller/arangodb,wiltonlazary/arangodb,wiltonlazary/arangodb,Simran-B/arangodb,fceller/arangodb,wiltonlazary/arangodb,graetzer/arangodb