#638 Check for DB error response before handling

[andrew-demb]

The code is unchecked, sorry for this. I can't build project locally.

It seems, what client is not checked for the error response from MongoDB.
I reproduced #638 by the direct request and get error
db.system.users.find()

Error: error: {
	"ok" : 0,
	"errmsg" : "not authorized on mydb to execute command { find: \"system.users\", filter: {} }",
	"code" : 13,
	"codeName" : "Unauthorized"
}

[andrew-demb]

Hey, anybody?

Ping.