Regression in bootstrapping in 3.4.7 around NRE in PruneNodes

When upgrading from 3.4.6 to 3.4.7 bootstrapping began to fail, showing this exception in the logs:

System.NullReferenceException: Object reference not set to an instance of an object. at Couchbase.Core.ClusterContext.<>c__DisplayClass70_0.<PruneNodes>b__1(IClusterNode x) at System.Linq.Enumerable.WhereEnumerableIterator`1.MoveNext() at Couchbase.Core.ClusterContext.PruneNodes(BucketConfig config) at Couchbase.Core.ClusterContext.ProcessClusterMapAsync(BucketBase bucket, BucketConfig config)

Based on review of the stack trace, I believe this is caused by the lack of a null check on IClusterNode.Owner here:

https://github.com/couchbase/couchbase-net-client/blob/b527bc98b681f89fae5954d7c1aad4eb01b49c35/src/Couchbase/Core/ClusterContext.cs#L834

I think this error probably existed before, but was being disguised until new error handling code was added in 3.4.7:

https://github.com/couchbase/couchbase-net-client/commit/7f3bf0f95142114b6453be6f4e26154fe884adbe#diff-ba5e9d3a81abb2d724c35296910c9b3a53782d6c9648fbcc3b4403cad8a60120R816

Now it throws the exception instead of simply logging and moving on.

In case it's a factor, the Couchbase Server details are:

• Couchbase Server 6.6.5 Enterprise
• Running in K8S via the Autonomous Operator
• Two buckets used by this service, one Couchbase and one Ephemeral
• MDS scaling with separate services per node

Application details:

• .NET 6 using ASP.NET Core MVC
• Using DI extensions
• Not using WaitUntilReadyAsync, simply requesting the bucket