Coverity analysis defect 105263: Dereference after null check

Pointer is checked against null but then dereferenced anyway

Defect 105263 (STATIC_C)
Checker FORWARD_NULL (subcategory none)
File: /src/mongo/db/service_context.cpp
Function mongo::ServiceContext::OperationContextDeleter::operator ()(mongo::OperationContext *) const
/src/mongo/db/service_context.cpp, line: 261
Comparing "client" to null implies that "client" might be null.

        if (client && client->session()) {