Fix file stream (#5592)

* much cleaner stream management

* change pipeline promise name, remove comments

* changeset

* Update .changeset/quick-shirts-cry.md

.changeset/quick-shirts-cry.md

@@ -0,0 +1,5 @@
+---
+'@keystone-next/keystone': patch
+---
+
+Fixed uncaught exception in file stream.

packages-next/keystone/src/lib/context/createFilesContext.ts

@@ -1,5 +1,6 @@
 import path from 'path';
 import crypto from 'crypto';
+import { pipeline } from 'stream';
 import filenamify from 'filenamify';
 import { FilesConfig, FilesContext } from '@keystone-next/types';
 import fs from 'fs-extra';
@@ -65,26 +66,18 @@ export function createFilesContext(config?: FilesConfig): FilesContext | undefin
       const { upload: mode } = config;
       const safeFilename = generateSafeFilename(filename, config.transformFilename);
       const writeStream = fs.createWriteStream(path.join(storagePath, safeFilename));
-      const observeStreamErrors: Promise<void> = new Promise((resolve, reject) => {
-        writeStream.on('close', () => {
-          resolve();
-        });
-        // reject on both writeStream and read stream errors
-        writeStream.on('error', err => {
-          reject(err);
-        });
-        stream.on('error', err => {
-          reject(err);
+      const pipeStreams: Promise<void> = new Promise((resolve, reject) => {
+        pipeline(stream, writeStream, err => {
+          if (err) {
+            reject(err);
+          } else {
+            resolve();
+          }
         });
       });
 
-      for await (let chunk of stream) {
-        writeStream.write(chunk);
-      }
-      writeStream.close();
-
       try {
-        await observeStreamErrors;
+        await pipeStreams;
         const { size: filesize } = await fs.stat(path.join(storagePath, safeFilename));
         return { mode, filesize, filename: safeFilename };
       } catch (e) {