Covert to ESM and get it functional locally

util/generateThumbnail.ts

@@ -5,15 +5,12 @@ import { access } from "fs/promises";
 import gm from "gm";
 import imageThumbnail from "image-thumbnail";
 import path from "path";
-import { logger } from "../server";
-import { AssetPaths, FolderPaths } from "./serverInit";
-const simpleThumb = require("simple-thumbnail");
+import { logger } from "../server.js";
+import { AssetPaths, FolderPaths } from "./serverInit.js";
+//@ts-ignore
+import simpleThumb from "simple-thumbnail";
 //const ffmpeg = require("ffmpeg-static");
 
-var Bluebird = require("bluebird");
-
-Bluebird.promisifyAll(gm.prototype);
-
 /** @returns {string} Returns the relative path from the file to the thumbnail on the server. This must be converted to a URL. */
 export default async function GenerateThumbnail(
   file: string
@@ -73,14 +70,17 @@ export default async function GenerateThumbnail(
 async function GeneratePdfThumbnail(file: string, thumbPath: string) {
   const fileOnDisk: Buffer = await fs.readFile(file);
   return new Promise<string>((resolve, reject) => {
-    const result = gm(fileOnDisk)
+    gm(fileOnDisk)
       .selectFrame(0)
       .setFormat("png")
-      .resize(200, 200, "!") // Resize to fixed 200px width, maintaining aspect ratio
+      .resize(200, 200, "!")
       .quality(75)
       .write(thumbPath, (error) => {
-        if (error) reject(error.message);
-        resolve(thumbPath);
+        if (error) {
+          reject(error);
+        } else {
+          resolve(thumbPath);
+        }
       });
   });
 }