[FAB-7399] Check for nil resources config

If the experimental resources tree support is enabled, but the genesis
block does not contain a seed resources tree, then an error is thrown
because the config is nil.  This CR simply checks for the nil case, and
if so, uses an empty resources tree as the seed.

Change-Id: I7c031d5c450cf9601175fc04a7d2c5355f051b7a
Signed-off-by: Jason Yellick <jyellick@us.ibm.com>

Author: Jason Yellick

core/peer/peer.go

@@ -337,10 +337,17 @@ func createChain(cid string, ledger ledger.PeerLedger, cb *common.Block) error {
 
 	resConf := &common.Config{ChannelGroup: &common.ConfigGroup{}}
 	if ac != nil && ac.Capabilities().ResourcesTree() {
-		if resConf, err = retrievePersistedResourceConfig(ledger); err != nil {
+		iResConf, err := retrievePersistedResourceConfig(ledger)
+
+		if err != nil {
 			return err
 		}
+
+		if iResConf != nil {
+			resConf = iResConf
+		}
 	}
+
 	rBundle, err := resourcesconfig.NewBundle(cid, resConf, bundle)
 
 	cs.bundleSource = resourcesconfig.NewBundleSource(