fix: check if OVF env is empty

It seems when you do not supply OVF env vars, the demarshalled XML turns
out with nil values. This commit adds checks for that.

Fixes #3513

Signed-off-by: Jorik Jonker <jorik.jonker@eu.equinix.com>

internal/app/machined/pkg/runtime/v1alpha1/platform/vmware/vmware_amd64.go

@@ -73,6 +73,12 @@ func readConfigFromOvf(extraConfig *rpcvmx.Config, key string) ([]byte, error) {
 		return nil, fmt.Errorf("failed to unmarshall XML from OVF env: %w", err)
 	}
 
+	if ovfEnv.Property == nil || ovfEnv.Property.Properties == nil { // no data in OVF env
+		log.Printf("empty OVF env")
+
+		return nil, nil
+	}
+
 	log.Printf("searching for property '%s' in OVF", key)
 
 	for _, property := range ovfEnv.Property.Properties { // iterate to check if our key is present