Add handling and logging for blobs that not block type

Author: Jeavon

src/UmbracoFileSystemProviders.Azure/AzureFileSystem.cs

@@ -783,11 +783,19 @@ private CloudBlockBlob GetBlockBlobReference(string path)
 
             string blobPath = this.FixPath(path);
 
+            var blobReference = this.cloudBlobContainer.GetBlobReferenceFromServer(blobPath);
             // Only make the request if there is an actual path. See issue 8.
             // https://github.com/JimBobSquarePants/UmbracoFileSystemProviders.Azure/issues/8
-            return !string.IsNullOrWhiteSpace(path)
-                ? this.cloudBlobContainer.GetBlockBlobReference(blobPath)
-                : null;
+            if (blobReference.BlobType == BlobType.BlockBlob && !string.IsNullOrWhiteSpace(path))
+            {
+                return blobReference as CloudBlockBlob;
+            }
+            else
+            {
+                Current.Logger.Error<AzureBlobFileSystem>($"A media item '{path}' was requested but it's blob type was {blobReference.BlobType} when it should be BlockBlob");
+                return null;
+            }
+
         }
 
         /// <summary>