fix Next.js image errors (#125)

use `:8080` for next custom server

Author: leoortizz

packages/firebase-frameworks/src/next.js/index.ts

@@ -12,10 +12,10 @@ const nextApp: NextServer = createNextServer({
   dev: false,
   dir: process.cwd(),
   hostname: "0.0.0.0",
-  port: 443,
+  port: 8080,
 });
 
-export const handle = async (req: Request, res: Response) => {
+export const handle = async (req: Request, res: Response): Promise<void> => {
   await nextApp.prepare();
   const parsedUrl = parse(req.url, true);
   const incomingMessage = incomingMessageFromExpress(req);