[release-1.17] Check for Auth.ServiceAccountName when the OIDC feature flag is switched on to avoid potential nil (knative#8583) (#1374)

* broom: when the OIDC feature flag is switched on, quickly before. It might be the case that the OIDC Service Account is not reconciled at that time



* Update pkg/reconciler/inmemorychannel/dispatcher/inmemorychannel.go



---------

Signed-off-by: Matthias Wessendorf <[email protected]>
Co-authored-by: Knative Prow Robot <[email protected]>
Co-authored-by: Christoph Stäbler <[email protected]>

Author: 3 people

pkg/reconciler/inmemorychannel/dispatcher/inmemorychannel.go

@@ -240,7 +240,7 @@ func newConfigForInMemoryChannel(ctx context.Context, imc *v1.InMemoryChannel) (
 		}
 
 		conf.Namespace = imc.Namespace
-		if isOIDCEnabled {
+		if isOIDCEnabled && sub.Auth != nil && sub.Auth.ServiceAccountName != nil {
 			conf.ServiceAccount = &types.NamespacedName{
 				Name:      *sub.Auth.ServiceAccountName,
 				Namespace: imc.Namespace,