refactor(downloader): improve structure and readability

internal/downloader/errors.go

@@ -0,0 +1,15 @@
+package downloader
+
+func handleError(err error) downloadResult {
+	if path, ok := IsSkipError(err); ok {
+		return downloadResult{
+			skipped: true,
+			path:    path,
+		}
+	}
+
+	return downloadResult{
+		success: false,
+		err:     err,
+	}
+}