Fixed a AdafruitShop test.

Props.Shop/Adafruit/AdafruitShop.cs

@@ -36,6 +36,7 @@ namespace Props.Shop.Adafruit
         );
         public async ValueTask Initialize(string workspaceDir, ILoggerFactory loggerFactory)
         {
+            workspaceDir = workspaceDir ?? "";
             this.workspaceDir = workspaceDir;
             this.loggerFactory = loggerFactory;
             logger = loggerFactory.CreateLogger<AdafruitShop>();
@@ -105,7 +106,6 @@ namespace Props.Shop.Adafruit
             LiveProductListingManager productListingManager = new LiveProductListingManager(http, loggerFactory.CreateLogger<LiveProductListingManager>(), listingData, configuration.MinDownloadInterval);
             this.searchManager = new SearchManager(productListingManager, configuration.Similarity);
             productListingManager.StartUpdateTimer(delay: 0, configuration.CacheLifespan);
-
         }
 
         public async Task<ProductListing> GetProductFromIdentifier(string identifier)