fix: hmr export default crash (#970)

Author: Alexander Vakrilov

hmr/hmr-update.ts

@@ -1,10 +1,10 @@
-import update from "../hot";
+import * as hot from "../hot";
 import { knownFolders } from "tns-core-modules/file-system";
 
 declare const __webpack_require__: any;
 
 export function hmrUpdate() {
     const applicationFiles = knownFolders.currentApp();
     const latestHash = __webpack_require__["h"]();
-    return update(latestHash, filename => applicationFiles.getFile(filename));
+    return hot(latestHash, filename => applicationFiles.getFile(filename));
 }