Sending proper Content-Type depending on file sent

const handler = async (req: Request): Promise<Response> => {
    const url = new URL(req.url);

    const filePath: string = "./client" + (url.pathname === "/" ? "/index.html" : url.pathname);

    try {
        const file = await Deno.open(filePath, {read: true});
        const readableStream = file.readable;
        
        return new Response(readableStream, {
            status: 200,
        })
    } catch (_error) {
        return new Response(`GET ${filePath}`, {status: 404});
    }
};