optmize location compare

internal/services/appconfiguration/app_configuration_resource.go

@@ -778,22 +778,19 @@ func expandAppConfigurationReplicas(input []interface{}, configurationStoreName,
 
 	// check if there are duplicated replica names or locations
 	// location cannot be same as original configuration store and other replicas
-	const placeholder = ""
-	locationSet := map[string]string{
-		configurationStoreLocation: placeholder,
-	}
+	locationSet := map[string]string{}
 	replicaNameSet := map[string]struct{}{}
 
 	for _, v := range input {
 		replica := v.(map[string]interface{})
 		replicaName := replica["name"].(string)
 		replicaLocation := location.Normalize(replica["location"].(string))
+		if strings.EqualFold(replicaLocation, configurationStoreLocation) {
+			return nil, fmt.Errorf("location (%q) of replica %q is duplicated with original configuration store %q", replicaName, replicaLocation, configurationStoreName)
+		}
 
 		if name, ok := locationSet[replicaLocation]; ok {
-			if name == placeholder {
-				return nil, fmt.Errorf("replica %q location %q is duplicated with original configuration store %q", replicaName, replicaLocation, configurationStoreName)
-			}
-			return nil, fmt.Errorf("replica %q location %q is duplicated with replica %q", replicaName, replicaLocation, name)
+			return nil, fmt.Errorf("location (%q) of replica %q is duplicated with replica %q", replicaName, replicaLocation, name)
 		}
 		locationSet[replicaLocation] = replicaName