refactor(server/utils): split stringifyStream function into two reusable functions

- bufferizeStream
  this concatenates stream data into a buffer
- stringifyStream
  this invokes `bufferizeStream` and converts the return value to a string

lib/functions.ts

@@ -35,17 +35,23 @@ export function isFicmasHidden(story: IStory): boolean {
 	);
 }
 
-export function stringifyStream(stream: GridFSBucketReadStream): Promise<string> {
+export function bufferizeStream(stream: GridFSBucketReadStream): Promise<Buffer> {
 	let chunks: Buffer[] = [];
+
 	return new Promise((res, rej) => {
 		stream.on("data", (c) => chunks.push(Buffer.from(c)));
 		stream.on("error", (err) => {
 			rej(err);
 		});
-		stream.on("end", () => res(Buffer.concat(chunks).toString("utf-8")));
+		stream.on("end", () => res(Buffer.concat(chunks)));
 	});
 }
 
+export async function stringifyStream(stream: GridFSBucketReadStream): Promise<string> {
+	let str = await bufferizeStream(stream);
+	return str.toString("utf-8");
+}
+
 export function norm(text: string): string {
 	return text
 		.replace(/\n/g, "<br>")