docs: Fix wishlist plugin example code (#3242)

added await to db query causing the value to be promise and causing server crash

Issue#2868

docs/docs/guides/developer-guide/plugins/index.mdx

@@ -358,7 +358,7 @@ export class WishlistService {
      */
     async addItem(ctx: RequestContext, variantId: ID): Promise<WishlistItem[]> {
         const customer = await this.getCustomerWithWishlistItems(ctx);
-        const variant = this.productVariantService.findOne(ctx, variantId);
+        const variant = await this.productVariantService.findOne(ctx, variantId);
         if (!variant) {
             throw new UserInputError(`No ProductVariant with the id ${variantId} could be found`);
         }

packages/dev-server/example-plugins/wishlist-plugin/service/wishlist.service.ts

@@ -33,7 +33,7 @@ export class WishlistService {
      */
     async addItem(ctx: RequestContext, variantId: ID): Promise<WishlistItem[]> {
         const customer = await this.getCustomerWithWishlistItems(ctx);
-        const variant = this.productVariantService.findOne(ctx, variantId);
+        const variant = await this.productVariantService.findOne(ctx, variantId);
         if (!variant) {
             throw new UserInputError(`No ProductVariant with the id ${variantId} could be found`);
         }