You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: client.go
    path of file: ./repos/convoy/internal/pkg/pubsub/google
    
    the code of the file until where you have to start completion: package google

import (
	"context"
	"errors"
	"fmt"

	"cloud.google.com/go/pubsub"
	"github.com/frain-dev/convoy/datastore"
	"github.com/frain-dev/convoy/pkg/log"
	"google.golang.org/api/option"
)

var ErrInvalidCredentials = errors.New("your google 
    
func (g *Google) Verify() error {
	ctx := context.Background()

	client, err := pubsub.NewClient(ctx, g.Cfg.ProjectID, option.WithCredentialsJSON(g.Cfg.ServiceAccount))
	if err != nil {
		log.WithError(err).Error("failed to create new pubsub client")
		return ErrInvalidCredentials
	}

	defer g.handleError(client)

	exists, err := client.Subscription(g.Cfg.SubscriptionID).Exists(ctx)
	if err != nil {
		log.WithError(err).Error("failed to find subscription")
		return ErrInvalidCredentials
	}

	if !exists {
		return fmt.Errorf("subscription ID with name %s does not exist", g.Cfg.SubscriptionID)
	}

	return nil
}