Fixed DQ Compute actor crash (#12987) (#13030)

Author: evanevanevanevannnn

ydb/library/yql/dq/actors/compute/dq_compute_actor_impl.h

@@ -1674,6 +1674,9 @@ class TDqComputeActorBase : public NActors::TActorBootstrapped<TDerived>
                     auto inputIndex = protoSource.GetInputIndex();
                     if (auto* sourceInfoPtr = SourcesMap.FindPtr(inputIndex)) {
                         auto& sourceInfo = *sourceInfoPtr;
+                        if (!sourceInfo.AsyncInput)
+                            continue;
+
                         protoSource.SetIngressName(sourceInfo.Type);
                         const auto& ingressStats = sourceInfo.AsyncInput->GetIngressStats();
                         FillAsyncStats(*protoSource.MutableIngress(), ingressStats);